CN117999494A - Megahertz sensor and related systems and methods - Google Patents

Abstract

Active Radio Frequency (RF) sensing techniques are described that determine relative and/or absolute states (e.g., position, velocity, and/or acceleration) of a target object (e.g., a person, car, truck, pole, building). The sensor described herein operates in the megahertz band (300 GHz to 3 THz). An active RF sensing device includes a substrate and first and second semiconductor dies mounted on the substrate. The first semiconductor die has an RF transmit antenna array integrated thereon, and the transmit antenna array includes a first plurality of RF antennas configured to generate RF signals having frequency components in the 300GHz to 3THz frequency band. The second semiconductor die has an RF receive antenna array integrated thereon, and the receive antenna array includes a second plurality of RF antennas configured to receive RF signals having frequency components in the 300GHz to 3THz frequency band.

Description

Megahertz sensor and related systems and methods

Cross reference to related applications

The present application claims 35U.S. C. ≡119 (e) attorney docket No. F0869.70000US00 entitled "TERAHERTZ SENSORS AND RELATED SYSTEMS AND METHODS", attorney docket No. 63/214,373 entitled "TERAHERTZ SENSORS AND RELATED SYSTEMS AND METHODS", attorney docket No. F0869.70000US01 entitled "TERAHERTZ SENSORS AND RELATED SYSTEMS AND METHODS", attorney docket No. F0869.70000US02 entitled "TERAHERTZ SENSORS AND RELATED SYSTEMS AND METHODS", and attorney docket No. 63/214,427 ", attorney docket No. F0869.70000US03, of 2021, 6, 24, each of which is incorporated herein by reference in its entirety.

Background

Autonomous vehicles, such as self-propelled vehicles, are vehicles equipped with sensors capable of sensing the surrounding environment, which assist in moving the vehicle without human intervention. Autonomous vehicles have been under development for decades. It is estimated that by 2024, at least to some extent, autonomous vehicles would account for more than half of all production vehicles. In recent years, billions of research and development have been devoted to fully autonomous vehicles. Nevertheless, development and deployment of fully autonomous vehicles requires significant advances in technology.

Disclosure of Invention

Some embodiments relate to a device comprising: a substrate defining a plane extending in a first direction and a second direction substantially orthogonal to each other; a first Radio Frequency (RF) antenna array mounted on the substrate and having a first aperture with a first width extending in the first direction and a first length extending in the second direction, the first length being greater than the first width; and a second RF antenna array mounted on the substrate and having a second aperture with a second width extending in the first direction and a second length extending in the second direction, the second length being less than the second width.

In some embodiments, the apparatus further comprises: RF transmission circuitry coupled to the first RF antenna array and configured to cause the first RF antenna array to transmit a first RF signal for determining a distance to a target object; RF receive circuitry coupled to the second RF antenna array and configured to receive second RF signals from the second RF antenna array, the second RF signals resulting from reflection of the first RF signals by the target object; and processing circuitry coupled to the RF receiving circuitry, the processing circuitry configured to determine a distance between the device and a target object.

In some embodiments, the processing circuitry is further coupled to the RF transmission circuitry.

In some embodiments, the first RF antenna array includes a first plurality of antennas sized to transmit megahertz RF signals, wherein the megahertz RF signals have frequency components in a frequency band of 300GHz to 3THz, and the second RF antenna array includes a second plurality of antennas sized to receive megahertz RF signals.

In some embodiments, the megahertz RF signals have a bandwidth in the range of 10GHz to 60 GHz.

In some embodiments, the first plurality of antennas comprises 4 to 128 antennas.

In some embodiments, the second plurality of antennas comprises 32 to 1024 antennas.

In some embodiments, the apparatus further comprises: a first semiconductor die mounted on the substrate, the first semiconductor die comprising the first RF antenna array, wherein the first plurality of antennas are integrated on the first semiconductor die.

In some embodiments, the apparatus further comprises: a second semiconductor die mounted on the substrate, the second semiconductor die including the second RF antenna array, the second plurality of antennas being integrated on the second semiconductor die.

In some embodiments, the apparatus further comprises: a first semiconductor die mounted on the substrate, the first semiconductor die comprising the first RF antenna array, the first RF antenna array comprising a first plurality of antennas integrated on the first semiconductor die, the first plurality of antennas sized to transmit megahertz RF signals having frequency components in the 300GHz to 3THz frequency band; and a second semiconductor die mounted on the substrate, the second semiconductor die including the second RF antenna array, the second RF antenna array including a second plurality of antennas integrated on the second semiconductor die, the second plurality of antennas sized to receive megahertz RF signals having frequency components in the 300GHz to 3THz frequency band.

In some embodiments, the first semiconductor die further comprises: the transmission circuitry; and a first redistribution layer coupling the first plurality of antennas to the transmission circuitry.

In some embodiments, the second semiconductor die further comprises: the receiving circuitry; and a second redistribution layer coupling the second plurality of antennas to the receive circuitry.

In some embodiments, the first semiconductor die comprises a first semiconductor type and the second semiconductor die comprises a second semiconductor type different from the first semiconductor type.

In some embodiments, the first semiconductor die comprises a III-V semiconductor.

In some embodiments, the first semiconductor die comprises indium phosphide.

In some embodiments, the second semiconductor die comprises silicon.

In some embodiments, the first semiconductor die comprises indium phosphide and the second semiconductor die comprises silicon.

In some embodiments, the length of the first aperture is between 5mm and 5cm and the width of the first aperture is between 0.1mm and 5mm.

In some embodiments, the length of the second aperture is between 0.1mm and 5mm, and the width of the second aperture is between 1cm and 18 cm.

In some embodiments, the first RF antenna array has a quasi-linear configuration.

In some embodiments, the second RF antenna array has a quasi-linear configuration.

In some embodiments, the first RF antenna array has a linear configuration.

In some embodiments, the second RF antenna array has a linear configuration.

In some embodiments, the first RF antenna array includes a first plurality of antennas sized to transmit RF signals having frequency components in a frequency band of 650 to 690GHz, and the first aperture is sized such that the first RF antenna array has an angular field of view in the first direction of between 50 and 150 in the frequency band of 650 to 690 GHz.

In some embodiments, the first RF antenna array includes a first plurality of antennas sized to transmit RF signals having frequency components in a frequency band of 650 to 690GHz, and the first aperture is sized such that the first RF antenna array has an angular field of view in the second direction of between 200 and 900 in the frequency band of 650 to 690 GHz.

In some embodiments, the apparatus further comprises signal generation circuitry configured to generate reference signals and provide the reference signals to the first RF antenna array and to the RF receive circuitry.

In some embodiments, the signal generation circuitry comprises: a signal generator configured to generate an initial RF signal; and up-conversion circuitry coupled to the signal generator, the up-conversion circuitry configured to generate the reference signal by up-converting the initial RF signal.

In some embodiments, the up-conversion circuitry includes a plurality of frequency multipliers for step up-converting the initial RF signal.

In some embodiments, the apparatus further comprises: a first semiconductor die mounted on the substrate, wherein the first semiconductor die comprises the first RF antenna array and at least a portion of the frequency up-conversion circuitry, and wherein the signal generator is mounted on the substrate.

In some embodiments, the signal generator is mounted on the substrate and the frequency up-conversion circuitry is mounted on the substrate.

In some embodiments, the initial RF signal has a time-varying center frequency.

In some embodiments, the time-varying center frequency of the initial RF signal varies linearly over time.

In some embodiments, the time-varying center frequency of the initial RF signal varies non-linearly over time.

Some embodiments relate to an apparatus comprising: a substrate; a first semiconductor die mounted on the substrate, the first semiconductor die having a Radio Frequency (RF) transmit antenna array integrated thereon; a second semiconductor die mounted on the substrate, the second semiconductor die having an RF receive antenna array integrated thereon; and signal generation circuitry mounted at least partially on the substrate, the signal generation circuitry coupled to the first semiconductor die and to the second semiconductor die.

In some embodiments, the signal generation circuitry comprises: an oscillator configured to generate a first signal; a signal generator configured to generate a second signal having a time-varying center frequency by frequency modulating the first signal; and up-conversion circuitry configured to generate a third signal by up-converting the second signal.

In some embodiments, the first signal has a center frequency in the range of 1GHz to 20GHz, and wherein the up-conversion circuitry is configured to up-convert the second signal by a factor between 30 and 80.

In some embodiments, the time-varying center frequency of the second signal varies linearly over time.

In some embodiments, the time-varying center frequency of the second signal varies non-linearly over time.

In some embodiments, the oscillator and the signal generator are mounted on the substrate, and a first portion of the up-conversion circuitry is integrated on the first semiconductor die.

In some embodiments, the second portion of the boost frequency conversion circuitry is mounted on the substrate.

In some embodiments, the boost frequency conversion circuitry comprises: a first plurality of frequency multipliers coupled to the RF transmit antenna array, wherein the first plurality of frequency multipliers is configured to upconvert respective input signals by a frequency multiplication factor; and a second plurality of frequency multipliers coupled to the RF receive antenna array, wherein the second plurality of multipliers is configured to upconvert respective input signals by the frequency multiplication factor.

In some embodiments, the first plurality of frequency multipliers is integrated on the first semiconductor die and the second plurality of multipliers is integrated on the second semiconductor die.

In some embodiments, the first plurality of frequency multipliers and the second plurality of frequency multipliers are mounted on the substrate.

In some embodiments, the signal generation circuitry further comprises a power divider and the frequency boost conversion circuitry comprises a plurality of frequency multipliers, wherein the power divider is configured to provide the second signal to at least some of the plurality of frequency multipliers.

In some embodiments, the frequency multipliers are coupled to respective antennas in the transmit RF antenna array, and wherein the power divider is configured such that the antennas in the RF transmit antenna array transmit RF signals in phase with respect to each other.

In some embodiments, the frequency multipliers are coupled to respective antennas in the transmit RF antenna array, and wherein the signal generation circuitry further comprises a plurality of phase shifters configured to cause the antennas in the RF transmit antenna array to transmit RF signals in phase with respect to each other.

In some embodiments, the plurality of frequency multipliers comprises a plurality of harmonic frequency multipliers.

In some embodiments, the RF transmit antenna array includes a plurality of RF antennas configured to transmit RF signals having frequency components in a frequency band of 300GHz to 3 THz.

Some embodiments relate to an apparatus comprising: a substrate; a first semiconductor die mounted on the substrate, the first semiconductor die having a Radio Frequency (RF) transmit antenna array integrated thereon, the transmit antenna array comprising a first plurality of RF antennas sized to transmit a first RF signal having a frequency component in a frequency band of 300GHz to 3 THz; and a second semiconductor die mounted on the substrate, the second semiconductor die having an RF receive antenna array integrated thereon, the receive antenna array including a second plurality of RF antennas sized to receive a second RF signal having a frequency component in the frequency band.

In some embodiments, the antennas of the first plurality of RF antennas are sized to transmit the first RF signals having frequency components in a frequency band of 650 to 690 GHz.

In some embodiments, the apparatus further comprises signal generation circuitry configured to generate reference signals having a bandwidth of 10GHz to 60GHz and provide the signals to the RF transmit antenna array, wherein the RF transmit antenna array is configured to transmit the first RF signals in response to receiving the reference signals from the signal generation circuitry.

In some embodiments, the first RF antenna array has a bandwidth of 10GHz to 60 GHz.

In some embodiments, the first semiconductor die further comprises: RF transmission circuitry coupled to the RF transmission antenna array and configured to cause the RF transmission antenna array to transmit the first RF signals; and a redistribution layer coupling the first plurality of RF antennas to the transmission circuitry.

In some embodiments, the apparatus further comprises processing circuitry coupled to the RF receive antenna array and configured to determine a distance between the apparatus and a target object using the second RF signals.

In some embodiments, the processing circuitry is further coupled to the RF transmit antenna array.

In some embodiments, the substrate defines a plane extending in first and second directions that are substantially orthogonal to each other, and wherein the RF transmit antenna array is configured to transmit the first RF signals in a third direction outside the plane.

In some embodiments, the third direction is substantially perpendicular to the plane.

In some embodiments, the second plurality of RF antennas are configured to generate differential signals in response to receiving the second RF signals.

In some embodiments, the second semiconductor die further comprises: a plurality of analog-to-digital converters (ADCs) coupled to the second plurality of RF antennas, the plurality of ADCs configured to digitize third RF signals generated by the second plurality of RF antennas in response to receiving the second RF signals.

In some embodiments, the second semiconductor die further includes a plurality of subharmonic mixers coupled to the second plurality of RF antennas and the plurality of ADCs, the subharmonic mixers configured to generate output signals by mixing the second RF signals with the reference signals generated by the signal generation circuitry and to provide the output signals to the plurality of ADCs.

In some embodiments, the plurality of subharmonic mixers includes a plurality of third harmonic mixers configured to mix the second RF signals with third harmonics of the plurality of reference signals.

In some embodiments, the plurality of subharmonic mixers includes differential inputs coupled to respective RF antennas of the second plurality of antennas.

In some embodiments, the plurality of subharmonic mixers further comprises a single-ended input configured to receive the reference signals generated by the signal generation circuitry.

In some embodiments, the second semiconductor die further includes a plurality of down-conversion mixers positioned between the plurality of subharmonic mixers and the plurality of ADCs, wherein the down-conversion mixers are configured to mix the output signals with the reference signals generated by the signal generation circuitry.

Some embodiments relate to a device comprising: a substrate; a first semiconductor die of a first semiconductor type mounted on the substrate, the first semiconductor die having a Radio Frequency (RF) transmit antenna array integrated thereon using a first semiconductor fabrication process; and a second semiconductor die of a second semiconductor type mounted on the substrate, the second semiconductor die having an RF receive antenna array integrated thereon using a second semiconductor manufacturing process different from the first semiconductor manufacturing process.

Some embodiments relate to a device comprising: a substrate; a first semiconductor die of a first semiconductor type mounted on the substrate, the first semiconductor die having a Radio Frequency (RF) transmit antenna array thereon; and a second semiconductor die of a second semiconductor type mounted on the substrate, the second semiconductor die having an RF receive antenna array thereon; wherein the first semiconductor type is different from the second semiconductor type.

In some embodiments, the second semiconductor type is a silicon-based semiconductor type, and the first semiconductor type is not a silicon-based semiconductor type.

In some embodiments, the first semiconductor type is a III-V semiconductor type.

In some embodiments, the first semiconductor type is an indium phosphide (InP) semiconductor type.

In some embodiments, the second semiconductor type is CMOS compatible.

In some embodiments, the second semiconductor type is a silicon/germanium-based semiconductor type.

In some embodiments, the first semiconductor type has an electron mobility at 300K between 3000cm ²V-1s^-1 and 5500cm ²V-1s^-1.

In some embodiments, the first semiconductor type has a current gain cut-off frequency (f _t) between 0.3THz and 1 THz.

In some embodiments, the first semiconductor type has a maximum oscillation frequency (f _max) between 0.7THz and 1.5 THz.

In some embodiments, the first semiconductor type has a breakdown electric field (E _bd) between 4×10 ⁵Vcm^-1 and 6×10 ⁵Vcm^-1.

In some embodiments, the apparatus further comprises processing circuitry coupled to the RF transmit antenna array and to the RF receive antenna array and configured to determine a distance between the apparatus and a target object.

In some embodiments, the RF transmit antenna array comprises a plurality of RF antennas, and wherein the apparatus further comprises signal generation circuitry configured to generate a first signal and a power divider configured to provide the first signal to the first plurality of RF antennas.

In some embodiments, the power splitter is configured to provide the first signal having the same phase to the first plurality of RF antennas.

In some embodiments, the RF transmit antenna array comprises a plurality of antennas, and wherein the apparatus further comprises signal generation circuitry configured to generate a first signal and a plurality of phase shifters configured to provide the first signal having the same phase to the first plurality of RF antennas.

In some embodiments, the RF transmit antenna array is sized to transmit RF signals in a frequency band of 300GHz to 3 THz.

In some embodiments, the RF transmit antenna array is configured to transmit the RF signal in the frequency band at a power level in the range of 10dBm to 30 dBm.

Some embodiments relate to a device comprising: a substrate; a first semiconductor die mounted on the substrate, the first semiconductor die having a Radio Frequency (RF) transmit antenna array integrated thereon; a second semiconductor die mounted on the substrate, the second semiconductor die having an RF receive antenna array integrated thereon; and a focusing element mounted on the substrate and configured to focus RF signals toward the RF receive antenna array.

In some embodiments, the focusing element is transparent in the frequency band of 300GHz to 3 THz.

In some embodiments, the focusing element is configured to focus RF signals having frequency components in a frequency band of 300GHz to 3THz toward the RF receive antenna array.

In some embodiments, the focusing element at least partially covers the RF receive antenna array and at least partially covers the RF transmit antenna array.

In some embodiments, the focusing element is a first focusing element at least partially covering the RF receive antenna array, and wherein the apparatus further comprises a second focusing element at least partially covering the RF transmit antenna array.

In some embodiments, the focusing element comprises a cylindrical lens having a principal axis extending parallel to the first axis.

In some embodiments, the RF receive antenna array has an aperture having a width extending parallel to the first axis and a length extending parallel to a second axis substantially orthogonal to the first axis, the width being greater than the length.

In some embodiments, the focusing element is formed of silicon.

In some embodiments, the focusing element comprises a spherical or elliptical lens.

Some embodiments relate to a device comprising: a substrate; a Radio Frequency (RF) transmit antenna array mounted on the substrate and configured to transmit a first RF signal having a power level (e.g., effective isotropic radiated power or EIRP) between 10dBm and 30dBm, the first RF signal having a frequency component in a frequency band of 300GHz to 3 THz; an RF receive antenna array mounted on the substrate and configured to receive a second RF signal generated by reflection of the first RF signal from a target object; and processing circuitry coupled to the RF transmit antenna array and to the RF receive antenna array, the processing circuitry configured to determine a distance of the target object relative to the device using the second RF signal, wherein the processing circuitry has a Noise Figure (NF) of between 10dB and 40 dB.

In some embodiments, the RF transmission array has a bandwidth of 15GHz to 25GHz and a distance resolution of between 6mm and 10 mm.

In some embodiments, the RF transmit antenna array has an aperture of between 1cm ² and 5cm ² and an angular resolution of between 0.4 ° and 1 ° in the frequency band.

In some embodiments, the substrate has an area between 10cm ² and 60cm ².

In some embodiments, the processing circuitry is configured to update the determination of the distance at a refresh rate between 0.1Hz and 100 Hz.

In some embodiments, the apparatus further comprises: a first semiconductor die mounted on the substrate, the first semiconductor die including the RF transmit antenna array, the RF transmit antenna array including a first plurality of antennas integrated on the first semiconductor die.

In some embodiments, the apparatus further comprises: a second semiconductor die mounted on the substrate, the second semiconductor die including the RF receive antenna array including a second plurality of antennas integrated on the second semiconductor die.

In some embodiments, the apparatus further comprises: a first semiconductor die mounted on the substrate, the first semiconductor die comprising the RF transmit antenna array, the RF transmit antenna array comprising a first plurality of antennas integrated on the first semiconductor die; and a second semiconductor die mounted on the substrate, the second semiconductor die including the RF receive antenna array, the RF receive antenna array including a second plurality of antennas integrated on the second semiconductor die.

In some embodiments, the first semiconductor die comprises indium phosphide and the second semiconductor die comprises silicon.

In some embodiments, the RF transmit antenna array comprises a first linear antenna array.

In some embodiments, the first linear antenna array comprises 4 to 128 antennas.

In some embodiments, the RF receive antenna array comprises a second linear antenna array.

In some embodiments, the second linear antenna array comprises 64 to 1024 antennas.

In some embodiments, the RF transmit antenna array includes a plurality of transmit antennas, each transmit antenna configured to transmit electromagnetic energy having a power level in the frequency band of between 1dBm and 2 dBm.

In some embodiments, the apparatus further comprises a focusing element mounted on the substrate and configured to focus a portion of the second RF signal to the RF receive antenna array.

Some embodiments relate to a method of imaging a target object using a device including a Radio Frequency (RF) transmit antenna array and an RF receive antenna array, the RF transmit antenna array having a first plurality of transmit antennas and a second plurality of transmit antennas. The method may comprise: transmitting a first RF signal having a frequency component in a frequency band of 300GHz to 3THz using the first plurality of antennas; transmitting a second RF signal having a frequency component in the frequency band using the second plurality of antennas; generating a first image at least in part by receiving a third RF signal generated by reflection of the first RF signal from the target object using the RF receive antenna array; generating a second image at least in part by receiving a fourth RF signal generated by reflection of the second RF signal from the target object using the receive antenna array; and determining a state of the target object using the first image and the second image.

In some embodiments, the first RF signal has a frequency component in a frequency band of 650GHz to 690 GHz.

In some embodiments, transmitting the second RF signal is performed after transmitting the first RF signal.

In some embodiments, generating the first image includes determining a phase of the third RF signal; generating the second image includes determining a phase of the fourth RF signal; and determining the state of the target object includes determining a difference between the phase of the third RF signal and the phase of the fourth RF signal.

In some embodiments, the transmit antenna array is oriented in a first direction and the receive antenna array is oriented in a second direction perpendicular to the first direction.

In some embodiments, determining the state of the target object includes determining a position of the target object relative to the device.

Drawings

Various aspects and embodiments will be described with reference to the following drawings. It should be understood that the drawings are not necessarily drawn to scale.

Fig. 1A is a diagram illustrating locations along the megahertz band of the electromagnetic spectrum.

FIG. 1B is a schematic diagram illustrating an autonomous vehicle including different types of sensors.

Fig. 2A is a plot illustrating Radio Frequency (RF) attenuation as a function of rainfall rate at different frequencies.

Fig. 2B is a table relating the type and intensity of precipitation to the rate of precipitation (R).

Fig. 2C is a plot illustrating solar spectral irradiance.

Fig. 3A is a plot illustrating RF atmospheric attenuation as a function of carrier frequency.

Fig. 3B is a diagram illustrating megahertz subbands suitable for performing ranging in accordance with some embodiments of the techniques described herein.

FIG. 4 is a table illustrating example system specifications in accordance with some embodiments of the technology described herein.

Fig. 5A illustrates a system for megahertz-based active sensing in accordance with some embodiments of the techniques described herein.

Fig. 5B-5C are side and top views, respectively, of a megahertz-based active sensor according to some embodiments of the techniques described herein.

Fig. 5D is a perspective view of a transmit antenna array in accordance with some embodiments of the techniques described herein.

Fig. 5E-1 is a perspective view of a receive antenna array in accordance with some embodiments of the techniques described herein.

Fig. 5E-2 are top views of a substrate including a transmit antenna array and a receive antenna array, according to some embodiments of the techniques described herein.

Fig. 5F is a top view of a substrate including multiple transmit antenna arrays and multiple receive antenna arrays, in accordance with some embodiments of the techniques described herein.

Fig. 5G is a flow chart illustrating a process for manufacturing a megahertz active sensor in accordance with some embodiments of the techniques described herein.

Fig. 5H is a cross-sectional view of a transmitter antenna die in accordance with some embodiments of the techniques described herein.

Fig. 5I is a cross-sectional view of another transmitter antenna die in accordance with some embodiments of the techniques described herein.

Fig. 5J is a cross-sectional view of another transmitter antenna die including a pair of TX antenna arrays, in accordance with some embodiments of the techniques described herein.

Fig. 6A is a block diagram illustrating signal generation circuitry according to some embodiments.

Fig. 6B is a plot illustrating the frequency of a signal over time according to some embodiments of the technology described herein.

Fig. 6C is a plot illustrating the frequency of another signal as a function of time in accordance with some embodiments of the technology described herein.

Fig. 6D is a block diagram illustrating up-conversion circuitry according to some embodiments.

Fig. 7A-7F are plots illustrating signal-to-noise ratio (SNR) as a function of distance according to some embodiments of the techniques described herein.

Fig. 8A is a schematic diagram illustrating a substrate including a plurality of transfer channels in accordance with some embodiments of the technology described herein.

Fig. 8B-8E are block diagrams illustrating various implementations of a transmission channel for fig. 8A in accordance with some embodiments of the technology described herein.

Fig. 9 is a block diagram illustrating a frequency multiplier according to some embodiments of the technology described herein.

Fig. 10A is a schematic diagram of a substrate including a plurality of receive antenna arrays, in accordance with some embodiments of the technology described herein.

Fig. 10B-10D are schematic diagrams illustrating a receive antenna die including a distribution network in accordance with some embodiments of the techniques described herein.

Fig. 10E is a block diagram illustrating a receive channel in accordance with some embodiments of the techniques described herein.

Fig. 11A-11B are schematic diagrams of signal mixers according to some embodiments of the technology described herein.

Fig. 12A is a side view of a megahertz active sensor in accordance with some embodiments of the technology described herein.

Fig. 12B is a side view of a megahertz active sensor including a focusing element in accordance with some embodiments of the technology described herein.

Fig. 12C is a schematic diagram illustrating a cylindrical lens in accordance with some embodiments of the technology described herein.

Fig. 12D is a top view of a megahertz active sensor including a focusing element in accordance with some embodiments of the technology described herein.

Fig. 12E is a side view of a megahertz active sensor including two focusing elements in accordance with some embodiments of the technology described herein.

Fig. 13 illustrates an example of a distance/cross-over full-distance image in accordance with some embodiments of the technology described herein.

Fig. 14A-14B are diagrams illustrating a system for multidimensional imaging in accordance with some embodiments of the technology described herein.

Fig. 14C is a diagram illustrating another system for multidimensional imaging in accordance with some embodiments of the technology described herein.

Fig. 14D-14I are diagrams illustrating yet another system for multidimensional imaging in accordance with some embodiments of the technology described herein.

Fig. 15 is a diagram illustrating segmentation of THz bands used to generate a multi-channel imaging system in accordance with some embodiments of the techniques described herein.

Fig. 16A is a diagram of a system including a TX antenna array configured to transmit multiple pulses, in accordance with some embodiments of the techniques described herein.

Fig. 16B illustrates an example of pulses in accordance with some embodiments of the techniques described herein.

Fig. 16C-16E are plots illustrating power of received signals as a function of distance according to some embodiments of the techniques described herein.

Fig. 16F is a plot illustrating integration rate as a function of distance in accordance with some embodiments of the technology described herein.

Fig. 16G is a plot illustrating frame rate as a function of distance in accordance with some embodiments of the technology described herein.

Fig. 17A is a plot illustrating signal-to-noise ratio versus distance in combination with a first ranging measurement, in accordance with some embodiments of the techniques described herein.

Fig. 17B is a plot illustrating signal-to-noise ratio versus distance in combination with second ranging measurements in accordance with some embodiments of the techniques described herein.

Fig. 18A is a photograph of an arrangement for performing ranging measurements including a THz ranging system and a plurality of objects, in accordance with some embodiments of the technology described herein.

Fig. 18B-18D are plots illustrating distance-cross-range measurements performed at different frequency ranges in conjunction with the setup of fig. 18A, according to some embodiments of the technology described herein.

Fig. 18E is a plot illustrating distance-cross full-distance measurements obtained by combining the measurements of fig. 18B-18D, in accordance with some embodiments of the technology described herein.

Fig. 19A is a photograph of another setup for performing ranging measurements including carriers, bicycles, and dummies, according to some embodiments of the technology described herein.

Fig. 19B-19D are plots illustrating distance-cross-over full-distance measurements performed at different frequency ranges in conjunction with the setup of fig. 19A, according to some embodiments of the technology described herein.

Fig. 19E is a plot illustrating distance-cross full-distance measurements obtained by combining the measurements of fig. 19B-19D, in accordance with some embodiments of the technology described herein.

Detailed Description

I. active sensing based on megahertz

The present inventors have developed active Radio Frequency (RF) sensing techniques operating in the megahertz band for determining relative and/or absolute states (e.g., position, velocity, and/or acceleration) of a target object (e.g., a static target object such as a street, furniture, light pole, utility pole, building, or a dynamic target object such as a person, car, truck, etc.). The terms "radio frequency" and "RF" are used herein to refer to electromagnetic signals having frequency components in the 0 to 3THz frequency band. The term "megahertz" is used herein to refer to radio frequency signals having frequency components in the 300GHz to 3THz frequency band (inclusive). This is illustrated in fig. 1A.

RF technology developed by the present inventors includes novel RF sensors, signal processing architecture, algorithms, and software. RF techniques developed by the present inventors and described herein may be used in a variety of applications. For example, RF technology may be used in the context of an autonomous vehicle, such as an autonomous vehicle, to determine the relative and/or absolute state of one or more target objects in the surrounding environment of the autonomous vehicle (e.g., the relative and/or absolute state of one or more vehicles, people, or other objects within a threshold distance of the autonomous vehicle). However, the techniques described herein may be used in connection with any type of vehicle, including, for example, land-based vehicles (e.g., automobiles, trucks, bicycles, motorbikes, and other wheel-based vehicles, as well as trains and other track-based vehicles), air-based vehicles (e.g., airplanes, helicopters, drones, etc.), space-based vehicles (e.g., satellites, spaceship, etc.), water-based vehicles (boats, barges, etc.), and any other type of vessel configured to carry a load (e.g., human, animal, plant, equipment, material, etc.).

Establishing reliable sensing capability of autonomous vehicles has been a major challenge for decades. Unfortunately, engineers have not identified a single type of sensor that can effectively monitor the surrounding environment in all conditions (e.g., rain, snow, fog, night, dense environments, etc.). Thus, existing approaches equip the carrier with multiple types of sensors, rather than relying on a single type of sensor. For example, as shown in fig. 1B, the carrier may be equipped with optical sensors (e.g., video cameras, infrared cameras), radio frequency sensors (e.g., RADAR sensors), and LIDAR sensors. This method is based on the following idea: having a set of different sensors provides better coverage than any sensor can provide individually, because each sensor has advantages and disadvantages.

For example, the optical sensor allows the carrier to maintain a 360 ° view of the external environment. Significant progress has been made in camera related technology in recent years, where ever-increasing resolutions can be achieved at lower prices than previously possible. By means of complex post-processing techniques, which typically involve machine learning, the optical sensor can detect and identify the object of the carrier. The ability of the optical sensor to distinguish colors improves the ability of the camera to distinguish dangerous situations from less risky situations. For example, the camera may easily identify other vehicles, pedestrians, riders, traffic signs and signals, guardrails, and the like. Unfortunately, optical sensors are still far from perfect. First, bad weather conditions (e.g., darkness, rain, snow, fog) significantly reduce the image quality, which significantly reduces the ability of the optical sensor to detect target objects in the roadway. Image quality also decreases when there is low contrast between objects or when objects are blended with the background (e.g., especially during sunny days). Second, the camera inherently produces two-dimensional data in which depth or distance information is not directly measured. Alternatively, depth or distance information may be obtained only after further signal processing is performed on the collected image and/or video data, which may be computationally demanding.

RADAR (radio detection and ranging) sensors are active detection sensors that use radio frequency signals to determine the relative and/or absolute state (e.g., position, velocity, and/or acceleration) of a target object. The RADAR sensor has at least one transmitter that transmits RF signals toward one or more items and at least one receiver that detects any RF signals reflected by the items. The detected RF signals are processed to determine absolute and/or relative (e.g., RADAR sensor) position, velocity, acceleration of the object. Unlike optical sensors, RADAR sensors are not susceptible to adverse weather conditions and directly detect depth or distance information.

Existing RADAR sensors for autonomous vehicles operate in the millimeter-wave band (i.e., 30GHz to 300 GHz) or at even lower frequencies. For example, one existing RADAR sensor operates in the 76GHz to 81GHz band. Existing RADAR sensors have limited spatial (e.g., distance and angular) resolution due to the (relatively long) wavelengths implied by operating in this frequency range. In practice, existing RADAR sensors used in automotive contexts have a range resolution of about several centimeters and a horizontal angular resolution of about 10 ° to 20 °. Thus, while existing RADAR sensors may identify the presence of a certain target object, they cannot reliably identify the nature or shape of the target object. For example, such existing RADAR sensors may not be able to distinguish pedestrians from carriers or roadway signals. An angular resolution of about 1 ° or less is necessary to distinguish the type of target object typically encountered on a road.

LIDAR (light detection and ranging) sensors operate similar to RADAR sensors, but at optical frequencies (e.g., in the infrared or visible portion of the electromagnetic spectrum) rather than radio frequencies. The location of the object is determined by transmitting the laser beam and by measuring the time it takes the reflected beam to hit the receiver. The LIDAR sensor has finer spatial resolution because the light has a wavelength that is substantially shorter than the wavelength at which existing automotive RADAR sensors operate.

However, LIDAR sensors also have several drawbacks. First, LIDAR sensors are significantly more susceptible to rain than RADAR sensors. This is because the size of the raindrops is comparable to the wavelength at which the LIDAR sensor operates. In heavy rain, the light emitted from the transmitter is scattered by the raindrops, which results in undesirable echoes. Second, the LIDAR sensor is susceptible to sunlight, which results in detector saturation, which in turn reduces the ability of the LIDAR sensor to detect objects. Thus, the LIDAR sensor works better at night.

The present inventors have recognized that existing methods using combinations of different types of sensors (e.g., video cameras, millimeter wave RADAR sensors, LIDAR sensors) provide limited performance at extremely high cost. Combining millimeter wave RADAR data with LIDAR data is computationally demanding (and therefore costly), particularly because such computations must be performed in real-time. Typically, millimeter wave RADAR data and LIDAR data are combined using a sensor fusion algorithm (e.g., an iterative state space algorithm such as a Kalman filter, an extended Kalman filter, a particle filter, etc.) that can leverage the benefits of such techniques to generate meaningful information about the dynamic properties of the target object, such as speed, angle, and location. Unfortunately, the computational complexity necessary to perform the fusion algorithm may be excessive, mainly due to its non-linear and iterative nature. Therefore, the carrier must be equipped not only with various types of sensors (which are themselves expensive), but also with a powerful computer to fuse its measurements, which further increases the cost so as to become impractical. Alternatively, using only some of these existing sensors and/or less computationally demanding fusion algorithms results in coverage gaps (e.g., if the deployed sensors are insufficient or if the computational complexity of the fusion algorithm is so high that the update rate is too low).

Accordingly, the present inventors have developed a new sensing technology for automotive and other autonomous vehicle applications that addresses the above-described shortcomings of existing sensors and sensor fusion technologies. In particular, the present inventors have developed novel RADAR sensors operating in the megahertz band that allow the sensor to incorporate some of the advantages of RADAR and LIDAR sensors (because THz radiation behaves partially like millimeter wave RF signals and partially like infrared light) while avoiding the need to use computationally expensive fusion algorithms. Sensing techniques developed by the inventors may be deployed on a vehicle (e.g., an automobile, whether autonomous or not) to aid in safety and operation, and in some embodiments, may completely replace existing RADAR and LIDAR sensors. However, it should be noted that in some embodiments, the sensing techniques developed by the present inventors may be used in conjunction with one or more existing sensors (e.g., video cameras, RADAR, LIDAR, etc.), as the aspects of the techniques described herein are not limited in this regard.

Furthermore, sensing techniques developed by the present inventors improve on existing RADAR and LIDAR sensors. For example, since the sensing technology developed by the present inventors operates in the megahertz band, it achieves significantly better spatial resolution than is possible with existing RADAR sensors. For example, the sensing technology developed by the present inventors achieves a distance resolution of about 6mm to 10mm and an angular resolution of about 0.4 ° to 1 °. This means that such systems can distinguish objects that are separated along the propagation axis, for example, by a distance as short as 8mm, or angularly separated, for example, by 0.6 ° (although in some embodiments, the angular resolution may be as low as 0.1 °). As described herein, existing RADAR sensors may achieve only a distance resolution of about several centimeters and an angular resolution of about 10 ° to 20 °, which is insufficient for automotive and other applications.

As another example, because megahertz signals have a longer wavelength relative to infrared signals, sensing techniques developed by the present inventors are less susceptible to scattering due to rain than LIDAR sensors. While megahertz signals are generally more susceptible to rain than millimeter waves, megahertz signals are less sensitive to changes in rain rates. Fig. 2A is a plot illustrating the specific attenuation of rainfall as a function of rainfall rate for various frequencies. At lower frequencies, the attenuation tends to be lower, but the slope of the curve tends to be higher. For example, at 40GHz, an increase in rainfall from 1mm/h to 100mm/h results in an increase in attenuation from 0.3dB/km to 25dB/km (spanning approximately two orders of magnitude variation). Thus, the performance of a sensing system operating at 40GHz may vary substantially from the start to the end of precipitation. Alternatively, at 840GHz the attenuation increases from 1dB/km at 1mm/h to 30dB/km at 100mm/h (spanning only a few orders of magnitude more variation). Thus, the effectiveness of the sensing system operating at 840GHz is more predictable throughout the duration of precipitation. Fig. 2B is a table relating the type and intensity of precipitation to the rate of precipitation (R). The rain at rates less than 0.1mm/h is considered light, at rates between 0.1mm/h and 0.5mm/h is considered medium, and at rates greater than 0.5mm/h is considered heavy. Rainfall at rates less than 2.5mm/h is considered mild, at rates between 2.5mm/h and 10mm/h is considered moderate, at rates between 10mm/h and 50mm/h is considered severe, and at rates greater than 50mm/h is considered extreme.

As yet another example, megahertz-based active sensing systems are less susceptible to sunlight than LIDAR sensors. Fig. 2C is a plot illustrating an example of solar spectral irradiance as a function of wavelength. As shown in the figure, most of the solar energy is concentrated in the visible and infrared regions, about 300nm to about 2000nm. This is why LIDAR sensors operating in this region are particularly susceptible to sunlight. In contrast, megahertz signals having wavelengths between 100 μm and 1mm are hardly affected by sunlight.

The megahertz-based active sensing system described herein may be used in autonomous vehicles, as well as in other contexts.

Regardless of the increasing demands for advanced autonomy, security, and capability, applications across multiple industries have been forced to rely on traditional sensors (cameras, LIDAR, and existing RADAR). While functional, such conventional sensors have several problems, as described herein. To realize the next generation of products, new capabilities are needed to correctly perceive the surrounding environment. The techniques described herein unlock a variety of new applications including new types of medical imaging (e.g., cancer detection and non-ionized dental imaging prior to treatment). Security applications may also be enhanced by new types of sensing, detecting objects such as guns or knives while protecting personal privacy. The technology described herein expands to provide a robust perception of autonomous platforms, including any of the vehicles described herein, regardless of weather, temperature, dust, or lighting. This robustness unlocks true autonomy in a comprehensive, secure manner in a variety of environments.

Other uses are also possible.

Despite the advantages described herein, the inventors have recognized that developing active megahertz-based sensing systems presents its own challenges, as described below.

II atmospheric attenuation

First, megahertz signals are more susceptible to atmospheric attenuation than millimeter wave or infrared light. Megahertz signals undergo absorption in the atmosphere by water vapor and oxygen molecules. For this reason, the atmospheric attenuation decreases with an increase in humidity. Fig. 3A is a plot illustrating the degree of atmospheric attenuation as a function of frequency at 60%, 80% and 100% humidity, respectively. At 100GHz, the atmospheric attenuation is well below 3dB/km, regardless of humidity. At 300GHz, the atmospheric attenuation is between 10dB/km and 40 dB/km. At 700GHz, the atmospheric attenuation is higher than 100dB/km.

Atmospheric attenuation poses a major challenge. The power level of the RF signal decays near or below the noise floor of the receiver as it travels from the transmitter to the target object and after being reflected from the target object to the receiver. Thus, the ability of the receiver to distinguish RF signals from noise is significantly reduced.

The present inventors have recognized several solutions to mitigate the effects of atmospheric attenuation. The solutions described herein may be used individually or in combination. One solution derives from the inventor's knowledge that atmospheric attenuation exhibits local attenuation minima. Fig. 3B is another plot illustrating the atmospheric attenuation as a function of frequency. Also, attenuation can be quite severe, up to 1000dB/km in some bands. Nonetheless, some bands exhibit local minima. For example, the atmospheric attenuation substantially drops in the frequency bands near 425GHz, 670GHz, and 850 GHz. Recognizing this behavior, active sensing systems according to some embodiments are designed to operate in one or more of these frequency bands where atmospheric attenuation exhibits local minima.

Another solution to mitigate the effects of atmospheric attenuation involves transmitting RF signals with high power levels. Transmitting RF signals with high power levels allows the receiver to receive enough energy to operate at the noise floor and produce an acceptable signal-to-noise ratio (SNR) (albeit with atmospheric attenuation). As an example, a transmitter according to some embodiments is designed to transmit power levels in excess of 10dBm in the megahertz band. Unfortunately, transmitting such power levels at such high frequencies is not straightforward. Existing silicon-based high frequency electronic amplifiers are not suitable for this task because they can operate at frequencies of tens of gigahertz at most. In some embodiments, high power transmission may be achieved using semiconductors with large current gain cut-off frequencies and/or large maximum oscillation frequencies.

The semiconductor material may be described with reference to the so-called "current gain cut-off frequency" (f _t) and by the so-called "maximum oscillation frequency" (f _max) as well as other parameters. These parameters quantify the actual upper frequency limit for proper circuit operation. In some embodiments, active sensing systems use transmitters having dies made of (or at least including) semiconductor materials having a current gain cutoff frequency exceeding, for example, 0.3THz, 0.5THz, or 0.7 THz. In some embodiments, active sensing systems use transmitters having dies made of (or at least including) semiconductor materials having maximum oscillation frequencies exceeding, for example, 0.5THz, 0.7THz, or 0.9 THz. Indium phosphide (InP) has the highest current gain cut-off frequency and highest maximum oscillation frequency among all semiconductor materials. In some embodiments, inP has a current gain cut-off frequency of up to 1THz and a maximum oscillation frequency of up to 1.5 THz. Thus, some embodiments include InP-based transmitters (although other materials are possible, as described herein). These types of transmissions may use a relatively small area (e.g., less than 1cm ²) to generate power levels in excess of 10 dBm.

Another solution to mitigate the effects of atmospheric attenuation involves focal plane arrays designed to increase (e.g., maximize) the amount of energy collected from reflected radiation. One way to increase the amount of energy collected is to use a very large antenna array. The larger the antenna array, the more energy the array can collect. Unfortunately, semiconductor materials such as InP used in some embodiments of transmit circuitry may not be suitable for receive circuitry because it is not possible to fabricate very large grains from such materials. Due to the poor mechanical properties of InP, it is often not feasible to manufacture large InP grains. In fact, inP tends to chip when manufactured in large areas. However, other semiconductor materials exist that are more resilient and thus allow for substantially larger grain areas. Silicon is one of these materials.

In recognition of the foregoing challenges, the inventors have developed hybrid transceivers, i.e., transceivers in which the transmitter die comprises one semiconductor material (e.g., inP) and the receiver die comprises another semiconductor material (e.g., si). For example, the transmitter die may be InP-based (such that the die substrate is made of InP and/or the transistors are made of InP). The receiver die may be silicon-based (such that the die substrate is made of silicon or silicon/germanium and/or the transistor is made of silicon or silicon/germanium). This dual semiconductor material approach enables, on the one hand, a high power transmitter and, on the other hand, a large area receiving antenna.

Accordingly, some embodiments relate to a device comprising: a substrate; a first semiconductor die of a first semiconductor type (e.g., inP) mounted on the substrate, the first semiconductor die having an RF transmit antenna array integrated thereon using a first semiconductor fabrication process; and a second semiconductor die of a second semiconductor type (e.g., si) mounted on the substrate, the second semiconductor die having an RF receive antenna array integrated thereon using a second semiconductor fabrication process different from the first semiconductor fabrication process.

To further increase the energy collected by the receiver, some embodiments use a focusing element. The focusing element enables the receiver to collect energy that would otherwise be lost. Focusing elements that may be used in some embodiments include cylindrical and spherical lenses, where the lenses are made of a material that is transparent in the megahertz band.

Accordingly, some embodiments relate to a device comprising: a substrate; a first semiconductor die mounted on the substrate, the first semiconductor die having an RF transmit antenna array integrated thereon; a second semiconductor die mounted on the substrate, the second semiconductor die having an RF receive antenna array integrated thereon; and a focusing element mounted on the substrate and configured to focus the RF signals toward the RF receive antenna array. In some embodiments, the focusing element is transparent in the frequency band of 300GHz to 3 THz. In some embodiments, the focusing element is configured to focus an RF signal having a frequency component in a frequency band of 300GHz to 3THz toward the RF receive antenna array. In some embodiments, the focusing element at least partially covers the RF receive antenna array and at least partially covers the RF transmit antenna array. In some embodiments, the focusing element is a first focusing element at least partially covering the RF receive antenna array, and wherein the device further comprises a second focusing element at least partially covering the RF transmit antenna array. In some embodiments, the focusing element includes a cylindrical lens having a principal axis extending parallel to the first axis. In some embodiments, the RF receive antenna array has an aperture having a width extending parallel to the first axis and a length extending parallel to a second axis substantially orthogonal to the first axis, the width being greater than the length. If the angle between the two axes is between 80 degrees and 100 degrees, the second axis is substantially orthogonal (or perpendicular) to the first axis. In some embodiments, the focusing element is formed of silicon. In some embodiments, the focusing element comprises a spherical or elliptical lens.

III state of the megahertz technology

Another challenge arises from the fact that megahertz technology is still in the initiation phase. Heretofore, no viable technology exists for generating and detecting megahertz radiation. In fact, at these frequencies, the techniques for power generation and detection are extremely inefficient. This problem is what scientists commonly call "megahertz gap". There is a gap between the more sophisticated millimeter wave technology on the RF side of the spectrum and the well-developed photonic technology on the infrared side of the spectrum. For this reason, the use of megahertz bands has been limited to very specific applications, such as sub-micron astronomy. Scientists have been trying to bridge this gap for decades. Some devices currently used for microwave generation, including vacuum electronics, may at least theoretically be modified to operate in the megahertz band. However, most of these devices are still in prototype form and are not reliable enough to meet the needs of commercial applications.

To avoid the lack of suitable megahertz generators and detectors, the present inventors have developed THz-based sensing systems in which signal generation and detection is performed at much lower frequencies. In some embodiments, the signal generator generates a reference signal frequency component in a low frequency band, and the up-conversion circuit converts the frequency component of the reference signal into a megahertz frequency band. An antenna transmits an upconverted signal that is received by another antenna after reflection from a target object. The frequency content of the received signal is down-converted to a lower frequency band, where the signal is detected and further processed.

In one example, on the transmitter side, the signal generator outputs a reference signal oscillating at 18.61GHz, and the up-conversion circuit up-converts the frequency component of the reference signal to 670GHz (i.e., having a frequency multiplication factor of approximately x 36). On the receiver side, the frequency content of the reference signal is down-converted from 670GHz back to 18.61GHz or lower.

Designing an antenna capable of transmitting and receiving in the megahertz band poses its own challenges. Finally, the size of the antenna is specified by the target wavelength. The higher the target frequency (and the lower the target wavelength), the smaller the antenna. As an example, the area of some antennas is approximately about λ2, where λ is the wavelength associated with the center frequency of the signal. At 1THz, for example, the area of the antenna should be about 90,000 μm2. Unfortunately, existing Printed Circuit Board (PCB) based antenna manufacturing techniques may not be able to achieve such smaller footprints. Microwave and millimeter wave antennas are currently manufactured using Printed Circuit Board Assembly (PCBA) technology. Metal is deposited on a Printed Circuit Board (PCB) and then patterned using photolithography and etching to define the desired shape. While the resolution of these photolithography tools is sufficiently precise for the production of microwave and millimeter wave antennas, it is far from adequate to define THz antennas. Generally, the cutoff value of PCBA-based antennas is about 150GHz to 200GHz. Antennas designed to operate below such frequencies may be fabricated using such techniques, while antennas designed to operate above such frequencies may be fabricated without such techniques.

To eliminate this limitation, in some embodiments, the megahertz antenna is fabricated using semiconductor fabrication processes and is thus integrated on a semiconductor die. The semiconductor manufacturing process provides finer resolution of the shadow that can be achieved using the PCBA manufacturing process. Thus, some embodiments pertain to on-chip megahertz antennas.

Accordingly, some embodiments relate to a device comprising: a substrate; a first semiconductor die mounted on the substrate, the first semiconductor die having an RF transmit antenna array integrated thereon, the transmit antenna array comprising a first plurality of RF antennas sized to transmit a first RF signal having a frequency component in a frequency band of 300GHz to 3 THz; and a second semiconductor die mounted on the substrate, the second semiconductor die having an RF receive antenna array integrated thereon, the receive antenna array including a second plurality of RF antennas sized to receive a second RF signal having a frequency component in the frequency band. In some embodiments, antennas of the first plurality of RF antennas are sized to transmit a first RF signal having a frequency component in a frequency band of 650 to 690 GHz. In some embodiments, the apparatus further comprises signal generation circuitry configured to generate a reference signal having a bandwidth of 10GHz to 60GHz and provide the signal to the RF transmit antenna array, wherein the RF transmit antenna array is configured to transmit the first RF signal in response to receiving the reference signal from the signal generation circuitry.

In some embodiments, the first RF antenna array has a bandwidth of 10GHz to 60 GHz. In some embodiments, the first semiconductor die further comprises: RF transmission circuitry coupled to the RF transmission antenna array and configured to cause the RF transmission antenna array to transmit a first RF signal; and a redistribution layer coupling the first plurality of RF antennas to the transmission circuitry. In some embodiments, the apparatus further includes processing circuitry coupled to the RF receive antenna array and configured to determine a distance between the apparatus and the target object using the second RF signal. In some embodiments, the processing circuitry is further coupled to an RF transmit antenna array. In some embodiments, the substrate defines a plane extending in a first direction and a second direction that are substantially orthogonal to each other, and wherein the RF transmit antenna array is configured to transmit the first RF signal in a third direction out of plane.

In some embodiments, the third direction is substantially perpendicular to the plane (e.g., between 80 degrees and 100 degrees). In some embodiments, the second plurality of RF antennas is configured to generate a differential signal in response to receiving the second RF signal. In some embodiments, the second semiconductor die further comprises: a plurality of analog-to-digital converters (ADCs) coupled to the second plurality of RF antennas, the plurality of ADCs configured to digitize a third RF signal generated by the second plurality of RF antennas in response to receiving the second RF signal. In some embodiments, the second semiconductor die further includes a plurality of subharmonic mixers coupled to the second plurality of RF antennas and the plurality of ADCs, the subharmonic mixers configured to generate output signals by mixing the second RF signals with reference signals generated by the signal generation circuitry and providing the output signals to the plurality of ADCs. In some embodiments, the plurality of subharmonic mixers includes a plurality of third harmonic mixers configured to mix the second RF signal with third harmonics of the plurality of reference signals. In some embodiments, the plurality of subharmonic mixers includes differential inputs coupled to respective RF antennas of the second plurality of antennas. In some embodiments, the plurality of subharmonic mixers further includes a single-ended input configured to receive a reference signal generated by the signal generation circuitry. In some embodiments, the second semiconductor die further includes a plurality of down-conversion mixers positioned between the plurality of subharmonic mixers and the plurality of ADCs, wherein the down-conversion mixers are configured to mix the output signal with a reference signal generated by the signal generation circuitry.

IV shape factor

Another challenge arises from the small form factor requirements of the sensor required by the carrier manufacturer. LIDAR sensors and existing RADAR sensors are typically very compact so that they can be mounted in close proximity to the headlights of the vehicle. Carrier manufacturers may be reluctant to employ sensors with larger footprints. Thus, the THz sensing system developed by the present inventors and described herein is packaged in a small form factor, for example to fit within the size of an existing business card (e.g., 9cm x 5 cm) or a pair of business cards (e.g., 18cm x 5 cm).

Reducing the size of the device is a challenge from a system design perspective. There is very limited space inside the package and the package must be wide enough to accommodate the large transmitters, large receivers, and electronics needed to perform ranging and/or other measurements. On the one hand, it is necessary to use a large aperture receiving antenna to collect as much energy as possible. Large transmit antennas are also desirable because the greater the number of transmit antennas, the greater the power level that the transmitter can transmit. On the other hand, the small space available within the package limits the size of the transmit and receive antennas, so some trade-offs need to be made.

To reduce the space occupied by the receiver, some embodiments use linear or quasi-linear antenna arrays. The linear antenna array is an N x 1 antenna array and the quasi-linear antenna array is an N x M antenna array, where N is at least fifty times greater than M, at least forty times greater than M, at least thirty times greater than M, at least twenty times greater than M, at least ten times greater than M, at least five times greater than M, or at least three times greater than M. While these types of arrays occupy nearly the entire width of the board in one direction, they release a larger area for other system components in the orthogonal direction. In addition, linear or quasi-linear antenna arrays do not significantly reduce the performance of the receiver relative to 2D arrays of nxn antennas. Indeed, sensing of autonomous vehicles may generally require a large field of view in the horizontal axis, which allows the system to see the target object surrounding the vehicle, while the field of view on the vertical axis does not have to be as large as possible. Further, some embodiments relate to a transmitter that is elongated in a vertical direction (i.e., in a direction that is substantially orthogonal to a direction in which the receiver extends). In other words, the aperture of the transmitter antenna array is relatively thin in the horizontal direction and relatively long in the vertical direction. This shape enables the conveyor to span a wide angle in the horizontal direction at the expense of a small angle in the vertical direction (which may be less important in some applications where the target object is moved horizontally or longitudinally to a greater extent than its vertical movement).

Some embodiments relate to a device comprising: a substrate (e.g., a PCB, package base, or other type of support) defining a plane extending in first and second directions that are substantially orthogonal to each other; an RF antenna array mounted on the substrate and having a first aperture with a first width extending in a first direction and a first length extending in a second direction, the first length being greater than the first width; and a second RF antenna array mounted on the substrate and having a second aperture with a second width extending in the first direction and a second length extending in the second direction, the second length being less than the second width. In some embodiments, the device further comprises: RF transmission circuitry coupled to the first RF antenna array and configured to cause the first RF antenna array to transmit a first RF signal for determining a distance to the target object; RF receive circuitry coupled to the second RF antenna array and configured to receive a second RF signal from the second RF antenna array, the second RF signal resulting from reflection of the first RF signal by the target object; and processing circuitry coupled to the RF receiving circuitry, the processing circuitry configured to determine a distance between the device and the target object. In some embodiments, the processing circuitry is further coupled to the RF transmission circuitry. In some embodiments, the first RF antenna array includes a first plurality of antennas sized to transmit megahertz RF signals, wherein the megahertz RF signals have frequency components in a frequency band of 300GHz to 3THz, and the second RF antenna array includes a second plurality of antennas sized to receive megahertz RF signals. In some embodiments, the megahertz RF signal has a bandwidth in the range of 10GHz to 60 GHz. In some embodiments, the first plurality of antennas comprises 4 to 128 (e.g., 10 to 50) antennas. In some embodiments, the second plurality of antennas comprises 64 to 1024 antennas. In some embodiments, the device further comprises: a first semiconductor die mounted on the substrate, the first semiconductor die comprising a first RF antenna array, wherein a first plurality of antennas are integrated on the first semiconductor die. In some embodiments, the device further comprises: a second semiconductor die mounted on the substrate, the second semiconductor die including a second RF antenna array, a second plurality of antennas being integrated on the second semiconductor die. In some embodiments, the apparatus further comprises: a first semiconductor die mounted on the substrate, the first semiconductor die comprising the first RF antenna array, the first RF antenna array comprising a first plurality of antennas integrated on the first semiconductor die, the first plurality of antennas sized to transmit megahertz RF signals having frequency components in the 300GHz to 3THz frequency band; and a second semiconductor die mounted on the substrate, the second semiconductor die including the second RF antenna array, the second RF antenna array including a second plurality of antennas integrated on the second semiconductor die, the second plurality of antennas sized to receive megahertz RF signals having frequency components in the 300GHz to 3THz frequency band. In some embodiments, the first semiconductor die further comprises: transmission circuitry; and a first redistribution layer coupling the first plurality of antennas to the transmission circuitry. In some embodiments, the second semiconductor die further comprises: receiving circuitry; and a second redistribution layer coupling the second plurality of antennas to the receive circuitry.

V. specification

An illustrative example of a system specification according to some embodiments is illustrated in the table of fig. 4. Of course, not all embodiments are limited to these particular values.

The present inventors have developed active megahertz-based sensing systems that meet the needs of autonomous vehicles. As is apparent from the description of the system link budget, the system developed by the present inventors can sense items located, for example, up to 200m away from the receiver, despite the large atmospheric attenuation that exists in the megahertz band. Under extremely dry conditions (e.g., less than 25% humidity), the system may sense items that are more than 200m away from it.

Some vehicles (e.g., automobiles and other land-based vehicles) tend to reflect more energy than pedestrians due to their larger cross-section. Thus, the sensing system may generally see the vehicle farther than it can see a pedestrian. As an example, the system may range up to 200m away of the vehicle in the presence of 60dB/km propagation loss, and up to 140m away of the vehicle in the presence of 100dB/km propagation loss. As another example, the system may range pedestrians up to 100m away in the presence of 60dB/km propagation loss, and up to 80m away in the presence of 100dB/km propagation loss.

The range resolution is a parameter that quantifies the ability of a RADAR sensor to distinguish between targets on the same bearing but at different distances. The smaller the distance resolution, the better the system's ability to distinguish between objects at different distances. A 10mm distance resolution indicates that objects separated by 10mm or more in distance are distinguishable from each other. The range resolution of the RADAR sensor is given by c/2B, where c is the speed of light in the medium of interest and B is the bandwidth of the signal. Operating in the megahertz band allows for a bandwidth that would not be possible in the millimeter wave case. In one example, the THz sensing system achieves a bandwidth of about 15 to 25 GHz. Given the inverse relationship between distance resolution and bandwidth, a bandwidth of about 15 to 25GHz achieves a distance resolution of only about several millimeters. In some embodiments, the systems described herein provide a distance resolution of about 6mm to 10 mm.

The angular resolution is a parameter that quantifies the ability of the RADAR sensor to distinguish between targets on different bearings at the same distance. The smaller the angular resolution, the higher the system's ability to distinguish objects. For existing RADAR, the angular resolution is equal to the aperture of the antenna beam, which in turn is related to the antenna linear size and signal wavelength. For an antenna having a linear dimension L and operating at a wavelength λ, the beam aperture (in radians) is approximately equal to 1.2 λ/L. Because of its lower wavelength, THz signals may achieve significantly better angular resolution than may be achieved with millimeter waves. An antenna having a linear dimension between 5cm and 20cm can achieve an azimuth resolution between 0.1 ° and 0.2 ° and an elevation resolution between 0.2 ° and 1 ° at 670 THz. In some embodiments, low angular resolution may be obtained, for example, using a transmit antenna array aperture between 1cm ² and 5cm ².

The sensitivity of the receiver is a parameter that quantifies the minimum signal strength that the receiver can accurately detect. The lower the sensitivity, the better the sensitivity, since the sensitivity indicates how weak the receiver can accurately receive the input signal. For example, a receiver with a sensitivity of-90 dBm is better than a receiver with a sensitivity of-80 dBm. Some sensing systems developed by the present inventors can achieve receiver sensitivity as low as-117.6 dBm for receivers with a Noise Figure (NF) of 10dB, 97.6 dBm for 20dB NF, 90.6dBm for 27dB NF, and 77.6dBm for 40dB NF. In some embodiments, NF is between 10dB and 40 dB. In some embodiments, NF is between 20dB and 40 dB. In some embodiments, NF is between 30dB and 40 dB.

In some embodiments, the systems described herein may provide a refresh rate (a rate of range image refresh, also referred to as a pulse repetition rate) between 2Hz and 50 Hz.

In some embodiments, the systems described herein may have a form factor with the following dimensions: a width of between 7cm and 11cm (e.g., 9 cm), a length of between 3cm and 7cm (e.g., 5 cm), and a depth of between 3cm and 7cm (e.g., 5 cm).

Some embodiments relate to a device comprising: a substrate; a Radio Frequency (RF) transmit antenna array mounted on the substrate and configured to transmit a first RF signal having a power level (e.g., EIRP) between 10dBm and 30dBm, the first RF signal having a frequency component in a frequency band of 300GHz to 3 THz; an RF receive antenna array mounted on the substrate and configured to receive a second RF signal generated by reflection of the first RF signal from a target object; and processing circuitry coupled to the RF transmit antenna array and to the RF receive antenna array, the processing circuitry configured to determine the distance of the target object relative to the device using the second RF signal, wherein the processing circuitry has a Noise Figure (NF) of between 10dB and 40 dB. The system may have a signal-to-noise ratio (SNR) of 13.4dB, which yields a detection probability of 0.95% and a false alarm probability of 0.000001%. In some embodiments, the RF transmission array has a bandwidth of 15GHz to 25GHz and a distance resolution of between 6mm and 10 mm. In some embodiments, the RF transmit antenna array has an aperture between 1cm ² and 5cm ² and an angular resolution between 0.4 ° and 1 ° in the frequency band. In some embodiments, the substrate has an area between 10cm ² and 60cm ².

In some embodiments, the processing circuitry is configured to update the determination of the distance at a refresh rate between 0.1Hz and 100 Hz.

VI hardware system

A. System architecture

Fig. 5A is a schematic diagram illustrating a carrier equipped with a megahertz (THz) active sensing system 1 according to some embodiments. Although THz active sensing system 1 is shown attached to the front bumper of an automobile, embodiments of the present technology are not limited to any particular location. Furthermore, the carrier may be equipped with more than one THz active sensing system 1. For example, a THz active sensing system may be attached to the front side of the carrier and another THz active sensing system may be attached to the back side. Other sensing technologies may be used alongside the THz sensing system including, for example, one or more optical sensors (e.g., video cameras and infrared cameras), one or more millimeter wave RADAR sensors, and/or one or more LIDAR sensors.

The THz active sensing system 1 comprises circuitry for determining the relative and/or absolute state (e.g. position, velocity and/or acceleration) of a target object using signals having frequency components in the frequency band of 300GHz to 3 THz. The THz active sensing system 1 comprises a transmitter, a receiver and processing circuitry (e.g. analog and/or digital circuitry). The transmitter transmits signals in the direction in which the target object may be present. For example, the signal may be transmitted along a road in front of the carrier. The receiver receives a signal resulting from reflection of the transmitted object from the target object. In this description, the transmitted signal is reflected from the backside of another carrier. Processing circuitry uses the received signals to determine the relative and/or absolute state of the target object. In some embodiments, the location of the target object may be determined based on measurements of distance relative to known locations of the sensing system. In some embodiments, the speed of the target object may be determined based on multiple measurements of distance (whether obtained from a single THz active sensing system 1 or from multiple THz active sensing systems 1). Similarly, the acceleration of the target object may be determined based on a plurality of velocity data points. The computer may use information obtained using the THZ sensing system to automatically control the vehicle in an aspect (e.g., to self-drive the vehicle without human intervention or with some degree of human intervention) or to perform other automated operations.

The x-axis will be referred to as the horizontal or azimuth axis, the y-axis as the vertical or elevation axis, and the z-axis as the longitudinal or separation axis. Fig. 5B-5C are side and top views, respectively, of a THz-active sensing system 1 according to some embodiments. The THz active sensing system 1 comprises a substrate 10, a Transmitter (TX) antenna array 102 and a Receiver (RX) antenna array 104. In some embodiments, the substrate 10 may include a Printed Circuit Board (PCB). In this description, the substrate 10 has a top surface extending in the xy plane. The THz active sensing system 1 may have a form factor small enough to fit into any suitable part of a carrier. The substrate 10 has a width W _S extending along the x-axis and a length LS extending along the y-axis. In some embodiments, the width W _S may be between 5cm and 15cm, between 9cm and 13, or between 7cm and 11 cm. In some embodiments, the length L _S may be between 1cm and 18cm, between 3cm and 7cm, or between 4cm and 6 cm. Other ranges are also possible. In some embodiments, the substrate has an area between 10cm ² and 60cm ².

TX antenna array 102 may be sized to transmit signals having frequency components in the frequency bands of 300GHz and 3THz or any frequency band within the 300GHz to 3THz frequency band. For example, TX antenna array 102 may be sized to transmit signals having frequency components in a frequency band of 650GHz to 690GHz or 660GHz to 680 GHz. In some embodiments, TX antenna array 102 has the following bandwidth (e.g., 3dB bandwidth): 4GHz to 134GHz, 4GHz to 100GHz, 4GHz to 60GHz, 10GHz to 100GHz, 10GHz to 60GHz, 10GHz to 30GHz, 15GHz to 60GHz, 10GHz to 30GHz or 15GHz to 25GHz. Similarly, the RX antenna array 104 may be sized to receive signals having frequency components in the frequency band of 300GHz to 3THz or any sub-band of this frequency band. For example, in some embodiments, RX antenna array 104 may be sized to receive signals having frequency components in a frequency band of 650GHz to 690GHz or 660GHz to 680 GHz. In some embodiments, the RX antenna array 104 has the following bandwidths: 10GHz to 60GHz, 10GHz to 30GHz, 15GHz to 60GHz, 10GHz to 30GHz, or 15GHz to 25GHz.

TX antenna array 102 and RX antenna array 104 may be disposed on substrate 10. For example, TX antenna array 102 and receiver RX antenna array 104 may be mounted directly on substrate 10, or may be integrated on one or more semiconductor die mounted on substrate 10. TX antenna array 102 may include multiple TX antennas and RX antenna array 104 may include multiple RX antennas. TX antenna array 102 may transmit signals out of a plane defined by the top surface of substrate 10 (e.g., parallel to the z-axis or at an angle other than 900 relative to the z-axis). For example, TX antenna array 102 may be shaped to have a main lobe that extends away from a plane defined by the top surface of substrate 10. Similarly, the RX antenna array 104 may receive the transmitted signal after reflection from the target object. For example, the RX antenna array 102 may be shaped to have a main lobe extending away from a plane defined by the top surface of the substrate 10.

As shown in fig. 5C, the aperture of TX antenna array 102 has a width W _TX extending along the x-axis and a length L _TX extending along the y-axis. In some embodiments, length L _TX is greater than width W _TX. For example, length L _TX may be more than four times greater than width W _TX, more than ten times greater than width W _TX, more than twenty times greater than width W _TX, or more than thirty times greater than width W _TX. The length L _TX may be between 10mm and 3cm, between 10mm and 5cm, between 10mm and 7cm, between 50mm and 3cm, between 50mm and 5cm, or between 50mm and 7 cm. The width W _TX may be between 0.1mm and 3mm, between 0.1mm and 5mm, or between 0.1mm and 10 mm. The aperture of TX antenna array 102 may be elongated along the y-axis to produce a larger horizontal field of view and a smaller vertical field of view. This is shown in the schematic diagram of fig. 5D, fig. 5D illustrating an example of a transmit cone for TX antenna array 102. The emission cone is elongated along the x-axis, which results in a larger horizontal field of view. In contrast, the emission cone is relatively narrow along the y-axis, which results in a smaller vertical field of view. TX antenna arrays are designed to have such an extended aperture because the target object is more likely to cross in the horizontal direction than in the vertical direction from the viewpoint of the front side of the carrier. Thus, computer-aided drive algorithms tend to benefit more from data points at different azimuth angles than from data points at different elevation angles. In one example, the angular field of view in the horizontal direction may be between 200 and 900 (e.g., in the 650GHz to 690GHz band), and the angular field of view in the vertical direction may be between 50 and 150 (e.g., in the 650GHz to 690GHz band).

Referring back to fig. 5c, the aperture of rx antenna array 104 has a width W _RX extending along the x-axis and a length L _RX extending along the y-axis. In some embodiments, width W _RX is greater than length L _RX. For example, width W _RX may be more than five times greater than L _RX, more than ten times greater than L _RX, more than twenty times greater than L _RX, or more than thirty times greater than L _RX. For example, the width W _RX may be between 5mm and 10cm, between 3cm and 10cm, or between 5cm and 10 cm. The length L _RX may be between 0.1mm and 3mm, between 0.1mm and 5mm, or between 0.1mm and 1 cm. The aperture of RX antenna 104 may be elongated along the y-axis to increase what is sensed by the array in the horizontal direction. As explained herein, from the viewpoint of the front side of the carrier, the target object tends to span more of the horizontal axis than it spans the vertical axis. This is shown in the schematic diagram of fig. 5E-1, fig. 5E-1 illustrating an RX antenna array 104 that extracts signals reflected along the horizontal axis from multiple directions. This depiction represents the context of the reflection of a signal from different angles. In some embodiments, one or more focusing elements may be used to perform viewpoint diversification, as described in detail herein.

Fig. 5E-2 is a top view illustrating the THz active sensing system in additional detail. As shown, the substrate 10 includes a TX die 12, an RX die 14, signal generation circuitry 16, and processing circuitry 18.TX die 12 and RX die 14 may be mounted on substrate 10 in any suitable manner, including, for example, using wire bonding techniques or flip chip techniques, etc. The signal generation circuitry 16 may be mounted on the substrate 10 or may be integrated on a die mounted on the substrate 10. In some embodiments, a portion of the signal generation circuitry 16 is mounted on the substrate 10 and another portion is integrated on one or more dies. For example, a first portion of the signal generation circuitry 16 may be mounted on the substrate 10, a second portion may be integrated on the TX 12 and a third portion may be integrated on the RX die 14.

TX die 12 includes a plurality of TX antennas 112 integrated thereon. TX antenna 112 may be of any suitable type including, for example, a patch antenna, a dipole antenna, and a slot antenna. In general, TX antenna 112 defines TX antenna array 102. Thus, the aperture of TX antenna array 102 represents the overall effective transmit area of the antenna. In some embodiments, TX antenna 112 defines a linear antenna array (an array of N x 1 antennas). In some embodiments, TX antenna 112 defines a quasi-linear antenna array (an array of n×m antennas, where N is at least thirty times greater than M, at least twenty times greater than M, at least ten times greater than M, at least five times greater than M, or at least three times greater than M). TX die 12 includes other components (not illustrated in fig. 5E-2) configured to drive an antenna, as will be described in detail herein.

In some embodiments, TX antennas 112 are configured to transmit in phase with respect to each other. In this way, the signals emanating from the array structurally interfere with each other and the overall transmit power level increases. As described herein, it is important to transmit sufficient power to overcome the severe atmospheric attenuation present in the THz frequency band. Different techniques may be used to ensure in-phase emissions. In some embodiments, passive circuits may be used to achieve in-phase transmission without having to control the phase of the signal. For example, TX die 12 may be designed to include a set of conductive traces that each feed one antenna, with the relative lengths of the conductive traces selected to ensure in-phase transmission (e.g., all having the same length). In some embodiments, in-phase transmission may be achieved using active circuitry. For example, each antenna (or at least some antennas) may be placed before a phase shifter. The phase shifter may adjust the phase of the signal driving the antenna to ensure that all (or at least a majority) of the antenna is transmitting in phase. In some embodiments, the TX antenna array may transmit at a power level greater than 10dBm (e.g., between 10dBm and 15dBm, between 10dBm and 20dBm, or between 10dBm and 30 dBm). For example, each antenna may transmit between 1dBm and 2dBm (e.g., 1.75 dBm) in the THz frequency band, and the array may include 4 to 128 antennas, 10 to 30 antennas, or 10 to 50 antennas (e.g., 16 antennas).

The RX die 14 includes a plurality of RX antennas 114 integrated thereon. For example, RX die 14 may include, for example, 32 to 1024 or 64 to 512 RX antennas 114. The RX antenna 114 may be of any suitable type including, for example, a patch antenna, a dipole antenna, and a slot antenna. In general, RX antenna 114 defines RX antenna array 104. Thus, the aperture of the RX antenna array 104 represents the overall effective reception area of the antenna. In some embodiments, RX antenna 114 defines a linear antenna array (an array of 1×m antennas). In some embodiments, RX antenna 114 defines a quasi-linear antenna array (an array of n×m antennas, where M is at least fifty times greater than M, at least forty times greater than M, at least thirty times greater than N, at least twenty times greater than N, at least ten times greater than N, at least five times greater than N, or at least three times greater than N). The RX die 14 includes other components (not illustrated in fig. 5E-2) that convey signals received from the antenna to processing circuitry 18.

The processing circuitry 18 may comprise digital and/or analog circuitry configured to determine the relative and/or absolute state of the target object based on reflected signals received from the RX antenna array. The processing circuitry 18 may be integrated on the RX die 14 or on another die, such as an ASIC or processor. In some embodiments, a portion of processing circuitry 18 is integrated on RX die 14 and a portion of processing circuitry 18 is integrated on another die.

In the example of fig. 5E-2, the substrate 10 includes only one TX die 12 and only one die RX die 14. In other embodiments, the substrate 10 may include more than one RX die, more than one TX die, or both. Fig. 5F illustrates an example in which the substrate 10 includes two TX dies 12 and three RX dies 14, but any other suitable number of TX dies and RX dies are possible. In some embodiments, the manufacturing process used to manufacture TX die 12 may limit the maximum number of antennas that may be formed on the die. Thus, having more than one TX die may emit more energy than would be possible with a single TX die. Similarly, in some embodiments, the manufacturing process used to manufacture RX die 14 may limit the maximum number of antennas that may be formed on the die. Thus, having more than one RX die may receive more energy than would be possible with a single RX die.

B. Semiconductor manufacturing process

The inventors have appreciated that TX and RX dies are configured to perform different functions and thus have different requirements. The TX die should be designed to transmit sufficient power in the megahertz band to overcome atmospheric attenuation. Thus, in some embodiments, one of the requirements of the TX die is to use high power, high frequency circuitry. On the other hand, the RX die should be designed to have a large number of antennas to increase the amount of received energy as much as possible. Thus, in some embodiments, one of the requirements of the RX die is that it be large enough to accommodate a particular threshold number of antennas. Although it is generally more practical and less costly to manufacture both TX and RX dies using the same semiconductor manufacturing process, the inventors have appreciated that it may be more suitable to manufacture dies using different semiconductor manufacturing processes given the specific requirements of TX and RX dies. Fig. 5G is a block diagram illustrating an example of a workflow for manufacturing the THz active sensing system 1. As shown in this figure, a first semiconductor fabrication process may be used to fabricate TX die 12 and a second semiconductor fabrication process may be used to fabricate RX die 14. Such semiconductor manufacturing processes may be performed in different manufacturing facilities, as there may not be a single manufacturing facility capable of handling both technologies. While the use of different manufacturing facilities may increase costs, the inventors have appreciated that in some embodiments, the increased costs result from performance improvement adjustments using different manufacturing facilities.

In some embodiments, the TX die comprises a first semiconductor type fabricated according to a first semiconductor fabrication process and the RX die comprises a second semiconductor type fabricated according to a second semiconductor fabrication process. In some embodiments, the second semiconductor type is a silicon-based semiconductor type, and the first semiconductor type is not a silicon-based semiconductor type. For example, the RX die may comprise silicon (e.g., the substrate of the RX die may be made of silicon and/or the transistor layer of the RX die may be made of silicon), and the TX die may comprise a III-V semiconductor (e.g., the substrate of the TX die may be made of III-V material and/or the transistor layer of the TX die may be made of III-V material), such as indium phosphide.

In some embodiments, two dies are considered to have different semiconductor types, wherein the substrate on which the dies are formed has different chemical compositions (e.g., a silicon-based substrate and any III-V-based substrate), and/or wherein the transistors of the dies are made of materials having different chemical compositions (silicon-based transistors and III-V-based transistors).

In view of the requirements of TX dies for high power, high frequency circuits, in some embodiments, the TX dies may be fabricated using semiconductor materials having a large maximum oscillation frequency f _max and/or a large current gain cutoff frequency f _t. The maximum oscillation frequency and the current gain cut-off frequency are parameters that quantify the upper limit of the actual frequency at which the applicable circuit operates. As an example, certain silicon/germanium (SiGe) processes may reach maximum oscillation frequencies in the range of 500GHz to 720 GHz. While the performance of SiGe-based devices may be adequate for sensing systems operating in the lower portion of the megahertz band, it may not be adequate for sensing systems operating at higher frequencies. For such systems, a maximum oscillation frequency exceeding 1THz and a current gain cutoff frequency exceeding 0.5THz would be desirable.

There are certain classes of semiconductor materials that provide such high f _max and f _t -materials with relatively high carrier (e.g., electron, hole) mobility and/or relatively high breakdown fields. In some embodiments, the transmitter may comprise a semiconductor material having an electron mobility at 300K between 3000cm ² V-1s-1 and 5500cm ² V-1s-1 and 5000cm ²V-1s^-1 and 5500cm ²V^-1s^-1. In some embodiments, the transmitter may include a semiconductor material having a breakdown electric field of 4×10 ⁵Vcm^-1 and 6×10 ⁵Vcm^-1.

Indium phosphide (InP) has the highest current gain cut-off frequency and maximum oscillation frequency for all semiconductor materials. Depending on the particular process used to fabricate the InP die, f _max may be up to 1.5THz (e.g., between 0.7THz and 1.5 THz) and f _t may be up to 1THz (e.g., between 0.3THz and 1 THz). In view of the large f _max and f _t in InP, some embodiments relate to TX dies that include InP (e.g., with InP substrates and/or with transistors made in InP). In some embodiments, TX dies that include InP-based circuitry (e.g., inP-based transistors and diodes) may be capable of transmitting electromagnetic energy in the megahertz band at a power level between 1dBm and 2dBm per antenna (e.g., 1.75 dBm).

Alternatively or additionally, other III-V semiconductor materials may be used. For example, some TX dies include gallium nitride (GaN), indium nitride (InN), aluminum nitride (AlN), gallium arsenide (GaAs), indium arsenide (InAs), aluminum arsenide (AlAs), gallium phosphide (GaP), and aluminum phosphide (AlP).

In view of the RX die requirements for large die areas that can accommodate as many antennas as possible, in some embodiments, the RX die may be fabricated using a semiconductor process that can produce large reticle sizes. Unfortunately, some of the semiconductor materials (e.g., inP) used in some embodiments of transmit circuitry may not be suitable for receive circuitry because it is not possible to fabricate very large dies from such materials. For example, large InP dies are not feasible using existing manufacturing processes due to the fragile nature of InP. InP tends to chip when manufactured in large areas.

Other semiconductor materials exist that are more resilient and thus provide a substantially larger grain area. Silicon is one of these materials. For example, some silicon fabrication processes may produce a reticle field as large as 110mm by 110 mm. This large reticle area can accommodate hundreds of RX antennas, thus realizing a very large RX antenna array. Thus, some embodiments relate to RX dies comprising silicon (e.g., with a silicon substrate and/or with a silicon transistor layer). An additional advantage of using silicon is the opportunity to fully utilize large scale CMOS compatible semiconductor foundry. To further improve its performance, some silicon RX-dies include SiGe transistors.

While in some embodiments, the TX die may be made of InP and the RX die may be made of Si as described herein, in other embodiments, the opposite configuration is also possible. In such embodiments, the system includes a high performance receiver rather than a high performance transmitter. In practice, while Si-based TX dies may not emit the amount of power possible with InP-based TX dies, inP-based RX dies may be significantly more sensitive than Si-based RX dies. Thus, in such embodiments, the lower power transmitted by the transmitter is constituted by the lower noise floor of the receiver.

In still other embodiments, the TX and RX dies may comprise the same semiconductor material (e.g., si or InP, etc.).

Some embodiments relate to a method of manufacturing a device, comprising: obtaining a first semiconductor die of a first semiconductor type and patterned by a Radio Frequency (RF) transmission antenna array, the first semiconductor die being fabricated using a first semiconductor fabrication process; obtaining a second semiconductor die of a second semiconductor type and patterned by the RF transmit antenna array, the second semiconductor die being fabricated using a second semiconductor fabrication process different from the first semiconductor fabrication process; and at least partially placing the first semiconductor die and the second semiconductor die on a substrate. In some embodiments, the second semiconductor type is a silicon-based semiconductor type and the first semiconductor type is a III-V semiconductor type. In some embodiments, the method further includes attaching the focusing element to the substrate such that the focusing element covers at least a portion of the RF receive antenna array. In some embodiments, the method further comprises: patterning the substrate with an RF power splitter having an input and a plurality of outputs prior to placing the first semiconductor die on the substrate; and after the first semiconductor die is placed on the substrate, coupling the output of the RF power splitter to respective ones of the RF transmission antennas via wire bonding.

C. Megahertz antenna

It is challenging to build an antenna capable of transmitting and receiving signals in the megahertz band. The size of the antenna is generally specified by the target wavelength. The area of the antenna is typically about lambda ², where lambda is the wavelength associated with the center frequency of the signal. At 1THz, for example, the area of the antenna may be about 90,000 μm ².

Microwave antennas are currently manufactured using Printed Circuit Board Assembly (PCBA) technology. Metal is deposited on a Printed Circuit Board (PCB) and then patterned using photolithographic techniques to form the desired shape. While the resolution of these photolithography tools is sufficiently precise for microwave and millimeter wave antennas, it is far from adequate to define megahertz antennas. Generally, the cutoff value of PCBA-based antennas is about 150GHz to 200GHz. Antennas designed to operate below such frequencies may be manufactured using such techniques, while antennas designed to operate above such frequencies are not manufactured using such techniques.

The inventors have appreciated that semiconductor manufacturing processes allow for significantly smaller features than are possible with PCBA manufacturing processes. Thus, in some embodiments, the antenna of the THz active sensing system 1 is integrated directly on the die. Fig. 5H is a cross-sectional view of TX die 12 including TX antenna 112 and transmit circuitry 113, according to some embodiments. TX antenna 112 is patterned on the top surface of TX die 12 and is coupled to transmit circuitry 113 via conductive trace 115. The transmission circuitry 113 may include transistors and/or other electronic components (including drivers, amplifiers, and frequency multipliers, examples of which are described in detail herein). The RX antenna 114 may be integrated on the RX die 14 in a similar manner. For example, RX die 14 may include receive circuitry, and an RX antenna may be coupled to the receive circuitry, similar to the configuration of fig. 5H. Examples of receive circuitry are described in detail herein.

Fig. 5I is a cross-sectional view of an alternative configuration. Here, TX antenna 112 is integrated with TX die 12, rather than being directly patterned on the top surface of the die, TX antenna 112 is positioned on top of the polymer layer. In this configuration, a polymer layer 127 is formed on the top surface of TX die 12. The conductive bump 117 passes through a portion of the polymer layer. Redistribution layers (RDLs) 107 and 109 and conductive bumps 117 route signals from TX die 12 to TX antenna 112. In this example, transmit circuitry 113 is coupled to TX antenna 112 via RDL. The RX antenna 114 may be integrated on the RX die 14 in a similar manner. For example, RX die 14 may include receive circuitry, and an RX antenna may be coupled to the receive circuitry, similar to the configuration of fig. 5I.

In some embodiments, the substrate 10 may include multiple TX antenna arrays, which may improve the overall spatial resolution of the system. For example, fig. 5J illustrates a substrate 10 including a pair of TX antenna arrays 102. The TX antenna array is positioned on the opposite side of the RX antenna array 104. In this way, the spacing between TX antenna arrays may be maximized (or at least increased) without having to increase the size of the substrate. When images obtained using a first TX antenna array are combined with images obtained using a second TX antenna array, increasing the spacing between the arrays results in an increase in the spatial resolution of the system (relative to a single TX antenna array implementation).

D. Signal generating circuit system

The inventors have appreciated that the generation and detection of signals directly in the megahertz band is not practical due to the absence of reliable signal generators and detectors in this band. Thus, in some embodiments, the megahertz sensing system 1 is configured to generate a reference signal having a relatively low frequency and upconvert the reference signal to a desired megahertz frequency band. On the transmitter side, the megahertz sensing system may translate frequency components of signals from a frequency band between 1GHz and 20GHz to a frequency band between 650GHz and 690 GHz. On the receiver side, the megahertz sensing system may translate frequency components of received signals from a frequency band between 650GHz and 690GHz to a frequency band between 1GHz and 20 GHz.

Furthermore, the inventors have appreciated that providing the same reference signal to both the transmitter and the receiver eliminates (or at least reduces) phase noise, which could otherwise occur if different reference signals were provided to the transmitter and the receiver. In practice, providing the same reference signal to the transmitter and receiver achieves phase coherence. Accordingly, some embodiments relate to signal generation circuits coupled to both transmitters and receivers. Fig. 6A illustrates one such system according to some embodiments. As depicted in this figure, signal generation circuitry 16 is coupled to TX antenna array 102 and receive circuitry 165 (which is further coupled to RX antenna array 104). As described herein, the receive circuitry 165 may be configured to down-convert signals received by the RX antenna array 104. The receive circuitry may down-convert the received signal using a signal generated by the up-conversion circuitry 164. In some embodiments, signal generation circuitry 16 may include an oscillator 160, a signal generator 162, and up-conversion circuitry 164. The signal generation circuitry 16 may be at least partially mounted on the substrate 10. For example, the oscillator 160 and the signal generator 162 may be mounted on the substrate 10. The frequency up-conversion circuitry 164 may be mounted on the substrate 10 or may be integrated on one or more semiconductor die. In one example, a portion of the boost frequency conversion circuitry 164 is partially integrated on TX die 12 and another portion of the boost frequency conversion circuitry is partially integrated on RX die 14.

The oscillator 160 may be configured to generate a first signal. The first signal may be a sinusoidal tone oscillating at a carrier frequency, for example, between 1GHz and 20 GHz. For example, the first signal may oscillate at 9.305GHz or 18.61 GHz. The signal generator 162 may be configured to generate a second signal having a time-varying center frequency (e.g., chirp) by frequency modulating the first signal. Thus, the second signal has a carrier frequency that varies over time. As described herein, the carrier frequency may vary (e.g., increase) linearly or non-linearly. The frequency up-conversion circuitry 164 may be configured to generate a third signal by frequency up-converting the second signal. Thus, the third signal has a frequency component that is substantially the same as (e.g., the same as, except for noise) the frequency component of the second signal, but the third signal transitions to a higher frequency band. The up-conversion 164 may be characterized by a frequency multiplication factor, which is a parameter that determines how many times the frequency of the second signal is multiplied. The multiplication factor may be, for example, between 30 and 80 (e.g., 36 or 72). In one example, the up-conversion circuitry may convert the frequency component of the second signal from a frequency of 9.305GHz to a frequency of 670GHz (i.e., where the multiplication factor is 72). In another example, the up-conversion circuitry may convert the frequency component of the second signal from a frequency of 18.61GHz to a frequency of 670GHz (i.e., wherein the multiplication factor is 36). The third signal is delivered to the various antennas of TX antenna array 102 and to the various antennas of RX antenna array 104. In this way, phase noise may be reduced.

Fig. 6B is a plot illustrating how the frequency and corresponding reflection of an RF signal may change over time according to some embodiments. In this example, the signal has a frequency that varies according to a linear ramp. This may be the result of the signal generator 162 modulating the frequency of the first signal with a linear ramp. The solid line represents the transmitted signal and the dashed line represents the reflected signal at the receiver. The frequency of the transmitted signal varies from frequency f ₁ at time t ₁ to frequency f ₂ at time t ₂. Therefore, the bandwidth of the transmitted signal is f ₂ to f ₁. In some embodiments, f ₁ may be, for example, 650GHz, 655GHz, 660GHz, or 665GHz. In some embodiments, f ₂ may be, for example, 690GHz, 685GHz, 680GHz, or 675GHz. The frequency of the reflected signal reflects the frequency of the transmitted signal with a delay Δt. The delay is equal to the round trip time of the transmitted signal after hitting the target object. Thus, the delay Δt quantifies the distance to the target object. The delay Δt can be obtained by determining the difference between the frequencies (Δf) of the signals at the specific time t 0. Since the chirp is linear, the delay Δt is given by the frequency difference Δf divided by the slope of the linear ramp. In some embodiments, Δf may be, for example, 6GHz, 10GHz, 20GHz, 30GHz, 40GHz, 50GHz, 60GHz, 80GHz, 100GHz, 120GHz, or 134GHz.

Fig. 6C is a plot illustrating a signal including two linear ramps, according to some embodiments. In this example, the first linear ramp is inclined in an upward direction (thus forming an upward ramp) and the second linear ramp is inclined in a downward direction (thus forming a downward ramp). The chirp allows the active sensing system to make two different measurements, one for each ramp. The first measurement (Δt ₁) is quantized to an initial distance to the target object and the second measurement (Δt ₂) is quantized to a final distance to the target object. The two measurements can be used to quantify the speed of the target object.

Fig. 6D depicts the boost frequency conversion circuitry 164 in additional detail, according to some embodiments. In this example, the boost frequency conversion circuitry 164 includes a power divider 111 and a plurality of frequency multipliers 122. The power divider 111 couples the second signal to various frequency multipliers. The frequency multiplier is disposed in the channel. Each channel couples a branch of the power divider to a corresponding antenna of TX antenna array 102 or to a corresponding channel of RX receive circuitry 165 and includes a plurality of frequency multipliers. Each frequency multiplier multiplies the frequency of the input signal by a predetermined amount. Thus, the up-conversion is performed in stages. In some embodiments, the frequency multiplier associated with the TX antenna array provides the same multiplication factor as the frequency multiplier associated with the RX antenna array.

The frequency multiplier may comprise a harmonic frequency multiplier. The harmonic frequency multiplier may generate a frequency that is a harmonic of the input frequency. In one example, each channel includes three harmonic frequency multipliers with the following multiplication factors: 3. 4, 3 (not necessarily in this order). Thus, the overall multiplication factor is 36. Such frequency multipliers may generate 670GHz of frequency from 18.61GHz of frequency. In another example, the channel includes four harmonic frequency multipliers with the following multiplication factors: 3. 4, 3, 2 (not necessarily in this order). Thus, the overall multiplication factor is 72. Such frequency multipliers may generate 670GHz from 9.305 GHz. In some embodiments, the frequency multiplier is mounted on the substrate 10. In some embodiments, the frequency multiplier coupled to TX antenna array 102 is integrated on TX die 12 and the frequency multiplier coupled to RX antenna array 104 is integrated on RX die 14.

E. Link budget

As described herein, the atmospheric loss that exists in the megahertz band can be quite significant. The architecture described herein enables accurate megahertz-based sensing systems despite atmospheric losses. The maximum distance that the system can sense the target object with acceptable accuracy is determined by several factors, including relative humidity, the nature of the detected target object, and signal-to-noise ratio (SNR) requirements. Generally, the higher the humidity, the higher the atmospheric loss, and thus, the smaller the maximum distance the system can sense the target object. As an example, at 670GHz, 60% humidity results in 100dB/km atmospheric loss, 80% humidity results in 200dB/km atmospheric loss, and 100% humidity results in 250dB/km atmospheric loss.

The nature of the target objects affects the performance of the system because different target objects may reflect more or less energy when hit by megahertz signals. Conductive surfaces tend to be more reflective than non-conductive surfaces. Larger target objects tend to reflect more power than smaller target objects because larger target objects have larger cross-sections. The angle at which the signal hits the target may also have an effect. RADAR Cross Section (RCS) is a parameter that quantifies the extent to which a target object can be detected via ranging. A larger RCS indicates that the target object is easier to detect. A typical RCS for an individual is approximately 0dBsm and a typical RCS for an average size car is 10dBsm across a wide range of frequencies, including for example at 670 GHz. In other words, the reflectivity of an automobile is ten times greater than the reflectivity of an individual.

SNR requirements are a measure of the minimum SNR at which the system can determine relative and/or absolute states (e.g., position, velocity, and/or acceleration) with acceptable accuracy. The SNR requirement of the system depends on several parameters including the power transmitted by the transmitter, the sensitivity of the receiver, the size of the receiver aperture, and the temperature of the receiver. Here, an SNR requirement of 13.4dB is provided. In some embodiments, the SNR requirement may be between 10dB and 15 dB.

Fig. 7A-7C are plots illustrating the system SNR as a function of distance (relative to the target) at 60% humidity. In these examples, each transmitter transmits 1.75dBm (or more generally, between 0.5dBm and 2 dBm) of power, and each RX antenna has a gain of 5dB (or more generally, between 3dB and 20 dB). The Noise Figure (NF) of the receiver is 30dB. The difference between the plots of fig. 7A-7C is the number of frames per second. In fig. 7A, sensing is performed at a rate of 1000 frames per second (fps). In FIG. 7B, sensing is performed at 10 frames per second, meaning with 100 fps-coherent integration. In FIG. 7C, sensing is performed at 2 frames per second, meaning with 500 fps-coherent integration. Each plot illustrates SNR requirements (which is set to 13.4dB, which in turn will yield a 95% detection probability and a 0.000001% false alarm probability), SNR corresponding to signals reflected by an automobile (10 dBsm), SNR corresponding to signals reflected by an individual, and atmospheric loss at 60% humidity. It should be noted that the main factor that the SNR corresponding to the reflected signal decreases with increasing range is the atmospheric loss. In fig. 7A, the SNR corresponding to the signal reflected by the car exceeds the SNR requirement at 73m. Thus, the maximum distance that the system can sense the target object under these conditions is 73m. Furthermore, the SNR corresponding to the signal reflected by the individual exceeds the SNR requirement at 50m. Thus, the maximum distance that the system can sense the target object under these conditions is 50m. As expected, the system measures farther from the car than the pedestrian. In fig. 7B, the SNR corresponding to the signal reflected by the car exceeds the SNR requirement at 126m, and the SNR corresponding to the signal reflected by the person exceeds the SNR requirement at 97 m. The maximum distance increases from fig. 7A to 7B due to the reduced frame rate. Finally, in fig. 7C, the SNR corresponding to the signal reflected by the car exceeds the SNR requirement at 147m and the SNR corresponding to the signal reflected by the person exceeds the SNR requirement at 117 m. Also, as the frame rate is further reduced, the maximum distance increases.

Fig. 7D to 7F are similar plots, but here the humidity is 80% instead of 60%. As expected, the SNR is reduced relative to the previous case. In fig. 7D (corresponding to 1000 fps), the SNR corresponding to the signal reflected by the car exceeds the SNR requirement at 51m, and the SNR corresponding to the signal reflected by the person exceeds the SNR requirement at 31 m. In fig. 7E (corresponding to 10 fps), the SNR corresponding to the signal reflected by the car exceeds the SNR requirement at 82m, and the SNR corresponding to the signal reflected by the person exceeds the SNR requirement at 65 m. In fig. 7F (corresponding to 2 fps), the SNR corresponding to the signal reflected by the car exceeds the SNR requirement at 93m, and the SNR corresponding to the signal reflected by the person exceeds the SNR requirement at 76 m.

F. Megahertz transmitter

Fig. 8A illustrates an example of megahertz transmitter circuitry in accordance with some embodiments. The signal generator 162 is configured to generate a signal having a time-varying center frequency, as described herein. The power splitter 111 couples the signal generator 162 to the TX die 12. In some embodiments, the power divider 111 is defined by conductive traces patterned on the substrate 10. Wire bonds 116 connect the ends of power divider 111 to the various channels of TX die 12. In some embodiments, power divider 111 may be designed such that channels receive copies of signals having the same phase. For example, the traces may all have the same length, or may have lengths that are adapted to compensate for known phase changes. This may ensure that the megahertz signals transmitted by the individual antennas are in phase, thereby maximizing the transmit power. In some embodiments, power divider 111 comprises a Wilkinson (Wilkinson) power divider.

In the example of fig. 8A, TX die 12 includes eight TX channels (201-208), but any other suitable number of channels is possible. Each channel conveys signals received from power divider 111 to a respective TX antenna 112. In this example, TX antenna 112 is implemented as a dipole antenna, although other antenna types are possible (including, for example, a patch antenna and a slot antenna). Each TX antenna 112 may be separated from adjacent antennas by a distance selected to cause in-phase transmission. For example, the spacing of the antenna arrays may be λ/2 (or an odd multiple of λ/2), where λ is the wavelength corresponding to the dominant (e.g., center) frequency of the emissions. Other spacings are also possible.

Fig. 8B-8E illustrate example implementations of the channels of TX die 12 according to some embodiments. In the implementation of fig. 8B, TX channel 201 includes pad 118, a plurality of frequency multipliers 122, and TX antenna 112 (in this example, a dipole). Wire bond 116 has one end connected to a branch of power divider 111 and one end connected to pad 118. Each frequency multiplier has a multiplication factor. The multiplication factors for the various frequency multipliers may be equal or different. In one example, there are three frequency multipliers with the following multiplication factors: 3.4, 3 (not necessarily in this order). In another example, there are four frequency multipliers with the following multiplication factors: 3.4, 3, 2 (not necessarily in this order). Other configurations are possible.

The frequency multiplier may be implemented in any of a number of ways. In some embodiments, the frequency multiplier may include a nonlinear circuit (e.g., one or more diodes) configured to generate one or more harmonics of the input frequency. Fig. 9 illustrates an example implementation of a frequency multiplier according to some embodiments. The frequency multiplier includes a diode 222 and a bandpass filter 223. Diode 222 receives a signal having a center frequency f ₀ and generates multiple harmonics (e.g., 2f ₀、3f₀、4f₀, etc.) of the input signal. The bandpass filter (BPF) 223 has a bandpass response centered around the harmonic of interest. For example, a frequency multiplier configured to generate a x3 multiplication factor includes a BPF having a response centered at 3f ₀. In other embodiments, the BPF may be omitted and the diode (or other nonlinear circuit) may be modified to amplify and/or attenuate the harmonic of interest. Transistor-based frequency multipliers are also possible.

Referring back to fig. 8B, the output of the last frequency multiplier is provided to TX antenna 112. The channel implementation of fig. 8C is similar to the implementation of fig. 8B, but further includes a driver 124 between the frequency multiplier and the TX antenna 112. The driver 124 may include, for example, a current driver and/or a buffer. The channel implementation of fig. 8D is similar to the implementation of fig. 7C, but it further includes a Power Amplifier (PA) 126 between the frequency multiplier and the TX antenna 112. In other embodiments, the TX channel may include PA126, but not driver 124. Finally, the channel embodiment of fig. 8E is similar to the embodiment of fig. 8D, but it further includes a phase shifter 128 between the pad 118 and the frequency multiplier. In some embodiments, phase shifter 128 may be controlled to compensate for any phase changes that occur between the various TX channels. Additionally or alternatively, the phase shifter 128 may be used to drive the antenna as a phased array. For example, the phase shifter may drive the antenna with a linear phase shift across the array such that the antenna transmits signals in a vertical axis at an angle relative to the z-axis. Furthermore, by periodically varying the phase shift, the emerging signal may be swept up and down, thus allowing the active sensing system to scan the vertical axis of the target object. In some embodiments, the driver 124 and/or PA126 may be omitted from the channel implementation of fig. 8E.

G. Megahertz receiver

Fig. 10A illustrates a portion of a substrate 10 including an RX die 14 according to some embodiments. RX die 14 includes receive circuitry 165 having multiple RX channels (e.g., RX channel 301). The RX die may include, for example, 128 channels, 256 channels, 512 channels, etc. (or another number, whether or not a power of 2). In some embodiments, the RX die may include more than 200 channels. Each channel includes an RX antenna 114, with the antennas separated from each other by a λ/2 spacing (or an odd multiple of λ/2), among other possible values. In addition, each channel receives a replica of the chirp signal via a respective branch of the power splitter 111. At each channel, the received signal is mixed with the chirp signal.

In some embodiments, the chirped signal may be up-converted to the frequency of the received signal in multiple stages. The first frequency multiplication stage may be located upstream of the distribution network and the second stage may be located downstream of the distribution network. Upconverting chirp signals in this manner may reduce the total power loss associated with upconverting operations relative to an architecture in which frequencies are upconverted in a single stage, whether upstream or downstream of a distribution network. One such architecture is illustrated in fig. 10B, according to some embodiments. Here, chirp signals enter the RX die from the bottom side. The level 1 multiplication unit up-converts the chirp signal to a specific frequency band. For example, the level 1 multiplication unit 318 may have a multiplication factor of 9. The 1:n distribution network 350 provides the upconverted chirp signals to the individual RX channels. Each channel mixes the upconverted chirp-modulated signal into a signal that is received by its antenna. The output of the mixer is provided to a readout ADC and serializer unit 300, which includes a plurality of analog-to-digital converters (ADCs) and serializers.

Fig. 10C-10D illustrate two possible implementations of a 1:n distribution network 350. In the embodiment of fig. 10C, the distribution network comprises a 1:n feed-through network with a tree of 3dB splitters. In the embodiment of fig. 10D, the distribution network comprises a traveling wave distribution network. The bus includes a plurality of taps branched from the bus.

Fig. 10E is a block diagram illustrating an example of an RX channel according to some embodiments. In this example, the RX channel includes a level 2 multiplication unit 320, which level 2 multiplication unit 320 further upconverts the frequencies generated from the level 1 multiplication unit 318. In some embodiments, the level 2 multiplication unit 320 has a multiplication factor selected such that the output signal has the frequency of the megahertz signal received by the antenna 114. For example, if the megahertz signal received by the antenna 114 has a center frequency of 670GHz, the chirped frequency signal output from the layer 2 multiplication unit 320 has a center frequency of 335 GHz. The power divider 325 divides the up-converted chirp signal into branches that are provided as inputs to the subharmonic mixer 310 and the down-conversion mixer 314, respectively. In this example, subharmonic mixer 310 receives the differential signal from RX antenna 114 and the upconverted chirp signal as a single ended input. The output of the subharmonic mixer is the signal received by the antenna, whose frequency is converted to half the frequency of the received signal.

The up-converted chirp appears as common mode noise at the differential output of the mixer. A Low Noise Amplifier (LNA) unit 312 comprising a plurality of LNAs provides gain and suppresses noise. Downstream of the LNA unit 312, the signal is mixed with an up-converted chirp signal, thereby converting the received signal to a mid-frequency.

Subharmonic mixer 310 may be implemented in any of a number of ways. In some embodiments, subharmonic mixer 310 receives two inputs, one differential and the other single ended. For example, the received signals are provided differentially and the upconverted chirp is provided in a single ended fashion. Subharmonic mixer 310 may be provided to output frequencies equal to f ₁ to nf ₂, where f ₁ and f ₂ are the frequencies of the input signals. The parameter n represents the order of the subharmonic mixers and may be, for example, equal to 2,3 or 4. In one example, f ₁ is the frequency of the input differential signal and f ₂ is the frequency of the input single-ended signal. The output of subharmonic mixer 310 may be differential.

In some embodiments, RX channel 301 may be implemented by a single sub-conversion stage. This RX channel may be similar to the implementation of fig. 10E, but may have only one of subharmonic mixer 310 and down-conversion mixer 314 instead of subharmonic mixer 310 and down-conversion mixer 314. In this configuration, a single mixer may be configured to down-convert the signal received from RX antenna 114 to a baseband frequency. Such implementations may or may not include a low noise amplifier unit 312.

Fig. 11A and 11B illustrate two possible implementations of subharmonic mixer 310 according to some embodiments. In both embodiments, the RX antenna 114 is directly coupled to the mixer (e.g., without a transmission line therebetween).

In the mixer of fig. 11A, RX antenna 114 is connected in series to the emitters of transistors T1 and T2. Here, the RX antenna 114 is a folded dipole coupled to ground. The bases of transistors T1 and T2 are connected to each other and the collectors are coupled to impedances 401 and 402, respectively. Transistors T1 and T2 may be of any suitable type including, for example, high Electron Mobility Transistors (HEMTs), bipolar complementary metal oxide semiconductor (BiCMOS) transistors, and Heterojunction Bipolar Transistors (HBTs), such as SiGe HBTs, and the like. Thus, the term "collector" encompasses both the collector and the drain, the term "emitter" encompasses both the emitter and the source, and the term "base" encompasses both the base and the gate. The up-converted chirp signal is provided at the base of the transistor in a single ended fashion. Thus, the transistors mix the signal received by the RX antenna with the upconverted chirp signal to produce a differential output (at the respective collectors of transistors T1 and T2).

In the mixer of fig. 11B, RX antenna 114 is connected in parallel to the emitters of transistors T1 and T2. Here, the RX antenna 114 is a dipole, each branch of which is connected to the emitter of a corresponding transistor. The emitter is further coupled to ground via impedances 411 and 412. As in the example of fig. 11A, the upconverted chirp signal is provided at the base of the transistor in a single ended fashion. Thus, the transistor mixes the signal received by the RX antenna with the upconverted chirp signal to produce a differential output.

H. Focusing element

The inventors have recognized that the active sensing system used in an autonomous vehicle should be small so that it can be housed on any suitable portion of the vehicle. Thus, in at least some embodiments, the inventors have designed the substrate 10 to have the approximate size of a business card or a pair of business cards. Unfortunately, having a small substrate area means that the space available for the RX antenna array is less than ideal. Thus, only a small portion of the energy reflected by the target object is collected. Fig. 12A is a side view of the substrate 10 illustrating the RX antenna array 104. As further shown in this figure, only a small portion of the reflected energy is collected—the energy that hits the RX antenna array 104. Energy hitting the substrate 10 outside the RX antenna array 104 is wasted. As described herein, increasing the length of the RX antenna array along the y-axis may not be an option, as this would take up space for other components.

Recognizing this problem, the present inventors have developed megahertz active sensing systems that use focusing elements to increase the collection of energy. Fig. 12B is another side view of the substrate 10 illustrating the RX antenna array 104. Furthermore, in this embodiment, the focusing element 400 is disposed near the RX antenna array 104. As shown in this figure, energy that hits the focusing element but otherwise would not hit the RX antenna array is now focused on the array. Therefore, this energy is also extracted, thus increasing the efficiency of the active sensing system. The focusing lens may be made of a material transparent in the megahertz band, such as silicon, or a polymer. The focusing element 400 may be positioned a distance from the top surface of the substrate 10 or may be in contact with that surface.

The focusing element may have any suitable shape configured to direct energy at a frequency of interest toward a surface of the RX antenna array 104. For example, the focusing element may be designed to provide focusing of at least between 650GHz and 690 GHz. In some embodiments, the focusing element may be implemented as a cylindrical lens, as shown in fig. 12C. The cylindrical lens 401 has a cylindrical or partially cylindrical shape. The principal axis 402 of the lens extends parallel to the height direction of the cylinder (or cylinder portion). In some embodiments, the major axis of the cylinder is parallel to the x-axis. In this way, the lenses focus waves that are offset from each other along the y-axis (as shown in fig. 12B), but do not focus waves that are offset from each other along the x-axis.

Other types of focusing elements are possible, including spherical or elliptical lenses. Spherical or elliptical lenses may be used in some embodiments to achieve viewpoint diversity. In such embodiments, waves incident on a spherical or elliptical lens from different angles in the xz plane may be focused on different areas of the RX antenna array. Viewpoint diversity may be achieved by interpreting different regions of the RX antenna array as being associated with different angles.

Fig. 12D-12E are top views of the substrate 10 according to some embodiments. In the embodiment of fig. 12D, the sensing system includes a focusing element 400 that covers both the TX and RX antenna arrays. In other embodiments, focusing element 400 may at least partially cover the TX antenna array and at least partially cover the RX antenna array. As described in connection with fig. 12B, the focusing element 400 may focus the incident THz signal on the RX antenna array. Optionally, the focusing element 400 may be further shaped to alter the signal transmitted by the TX antenna array, for example to focus the signal on a particular plane. For example, the focusing element 400 may include a dual focusing lens.

In the embodiment of fig. 12E, the sensing system includes a focusing element 400 covering the RX antenna array and a focusing element 401 covering the TX antenna array. In this way, one focusing element may be optimized to focus the incident wave on the RX antenna array, and separately, the other focusing element may be optimized as needed to shape the transmit signal.

Multidimensional imaging

The inventors have further developed systems and methods for imaging a target object in multiple dimensions (which may be used in connection with any of the hardware implementations described herein). For example, some embodiments pertain to systems and methods for imaging a target object in two dimensions (e.g., along a longitudinal axis and an elevation axis or along a longitudinal axis and an azimuth axis) or in three dimensions (along a longitudinal axis, an elevation axis, and an azimuth axis). The multi-dimensional image provides a more complete image of the surrounding area relative to the one-dimensional image.

An image of the type described herein includes a dataset that spatially correlates characteristics of a reflected wave (e.g., amplitude, power, or phase of the reflected wave). For example, a one-dimensional image may include a dataset relating the power of the reflected wave to the longitudinal axis. Each portion along the longitudinal axis corresponds to a value representing the characteristic of the reflected wave. As another example, the two-dimensional image may include a dataset relating the power of the reflected wave to the longitudinal axis and the azimuth axis (distance-cross full-range image), or a dataset relating the power of the reflected wave to the longitudinal axis and the elevation axis. An example of a distance/cross-over full-distance image is depicted in fig. 13. Here, the y-axis represents the longitudinal direction, and the x-axis represents the azimuthal direction. The two axes are discretized, thereby forming a two-dimensional grid. Each element of the grid corresponds to a value representing the power of the reflected signal. The image of fig. 13 includes two features 1301 and 1302. Each characteristic indicates the presence of a particular location of the target object in space relative to the transmitter/receiver. As another example, the three-dimensional image may include a dataset relating the power of the reflected signal to the longitudinal axis, azimuth axis, and elevation axis. In some embodiments, imaging an object involves generating a dataset that correlates a characteristic of the reflected wave (e.g., amplitude, power, or phase of the reflected wave) with space in one, two, or three dimensions.

Information about the elevation axis may be obtained using interferometric Synthetic Aperture RADAR (SAR) techniques. These systems generate a plurality of images each corresponding to a different viewpoint relative to the elevation axis. Each image is characterized by a phase (the phase of the return signal at the receiver). The phase of the return signal depends on the distance to the object, since the path length to the object and back includes several wavelengths plus some fraction of the wavelength. Imaging with respect to the elevation axis may be obtained by determining the difference between the phases of the different images.

Fig. 14A-14B are diagrams illustrating a system capable of imaging an object in multiple dimensions, according to some embodiments. In this configuration, information in the elevation axis is obtained by transmitting THz signals at different times with different subsets of the TX antenna array 102. At time t ₁, antennas 1,2, and 3 transmit (see fig. 14A). At time t ₂ (after t ₁), antennas 4, 5, and 6 transmit (see fig. 14B). Since the subsets are offset from each other along the elevation axis, different viewpoints are created with respect to each other. In some embodiments, TX antenna array 102 may be segmented in more than two subsets. Signals reflected in response to transmissions from a first subset of TX antenna arrays 102 and signals reflected in response to transmissions from a second subset of TX antenna arrays 102 are received by RX antenna arrays 104. Thus, the system generates two images. The system may determine the difference between the phases of the images and may use the phase difference to obtain information about the elevation axis.

In the configuration of fig. 14C, different viewpoints are obtained by providing a plurality of RX antenna arrays offset from each other along the elevation axis. In this configuration, the antennas of the TX antenna array may transmit simultaneously and the reflected signals are received by each of the RX antenna arrays.

Additionally or alternatively, information relative to the elevation axis may be obtained using time domain multiple input multiple output (TD-MIMO) techniques. According to some embodiments, one example of such a system is depicted in fig. 14D. In this sequence, the antennas of TX antenna array 102 transmit at different times. In some embodiments, imaging using TDMA-MIMO technology may utilize one antenna transmission at a time, while receiving on all receivers until a complete multi-dimensional data matrix is collected. In some embodiments, the system may calculate a three-dimensional image using, for example, SAR techniques for azimuth and MIMO techniques for elevation.

Some embodiments relate to a method of imaging a target object using a device including a Radio Frequency (RF) transmit antenna array and an RF receive antenna array, the RF transmit antenna array having a first plurality of transmit antennas and a second plurality of transmit antennas. The method may comprise: transmitting a first RF signal having a frequency component in a frequency band of 300GHz to 3THz using the first plurality of antennas; transmitting a second RF signal having a frequency component in the frequency band using the second plurality of antennas; generating a first image at least in part by receiving a third RF signal generated by reflection of the first RF signal from the target object using the RF receive antenna array; generating a second image at least in part by receiving a fourth RF signal generated by reflection of the second RF signal from the target object using the receive antenna array; and determining a state of the target object using the first image and the second image. In some embodiments, the first RF signal has a frequency component in a frequency band of 650GHz to 690 GHz. In some embodiments, transmitting the second RF signal is performed after transmitting the first RF signal. In some embodiments, generating the first image includes determining a phase of the third RF signal; generating the second image includes determining a phase of the fourth RF signal; and determining the state of the target object includes determining a difference between the phase of the third RF signal and the phase of the fourth RF signal. In some embodiments, the transmit antenna array is oriented in a first direction and the receive antenna array is oriented in a second direction perpendicular to the first direction. In some embodiments, determining the state of the target object includes determining a position of the target object relative to the device.

The object may be imaged relative to azimuth using various methods. For example, some embodiments use a back projection method, a range migration algorithm (e.g., an Ω -k algorithm), a polar formatting method (e.g., a polar format algorithm), or any combination thereof. Some of these methods may involve wavefront interpolation units, matched filters (e.g., complex multiplication of distance and cross-over whole data set per image), and two-dimensional Fast Fourier Transforms (FFTs) (e.g., inverse FFTs or IFFTs).

Multichannel imaging

With full exploitation of the large bandwidth achievable in the THz band, the inventors have developed techniques for multichannel imaging. Consider a system such as the type described herein and operating at frequencies in the range of 660 to 680 GHz. The inventors have recognized that a 20GHz bandwidth may be sufficient to produce not only one high resolution image, but also multiple high resolution images. For example, a 20GHz bandwidth may be segmented in three sub-bands each having a bandwidth of 6.66 GHz. Each sub-band has sufficient bandwidth to produce a range resolution as low as several centimeters.

In some embodiments, images are generated from each subband, and the images may be combined together to form a multi-channel image. The images may include different content relative to each other, thereby increasing the richness of the data. In practice, the object may reflect signals differently at different sub-bands. Depending on the shape and/or material of the article, the article may reflect more in one of the subbands than in the other subbands.

Fig. 15 is a diagram illustrating THz bands segmented in multiple sub-bands according to some embodiments. In this example, the bandwidth BW of the signal is segmented in three subbands (although it may be segmented in any suitable number of subbands, such as 2, 4,6, 7, 8, 9, 10, etc.). In some embodiments, a first image is generated based on a first sub-band, a second image is generated based on a second sub-band, and a third image is generated based on a third sub-band. After reflection from the target object, each sub-band of the signal may extract slightly different information about the target object relative to the other sub-bands. Thus, each image may have slightly different content. In some embodiments, images obtained from different subbands are combined to produce a multi-channel image. In some embodiments, a multi-channel image may be provided as input to train a machine learning model. In some embodiments, the multi-channel image may be provided as input to a previously trained machine learning model to identify the presence and/or characteristics (e.g., properties, composition) of the object.

In some embodiments, each image may be colored with a particular color. For example, each image may be assigned a particular color, and each image may be displayed according to the assigned color. For example, the image corresponding to the first sub-band of fig. 15 may be displayed in red, the image corresponding to the second sub-band of fig. 15 may be displayed in green, and the image corresponding to the third sub-band of fig. 15 may be displayed in blue. In some embodiments, the images thus obtained are combined to produce a multi-color image (multi-channel image, where each channel corresponds to a different color). Examples of composite images generated in this manner are shown in fig. 18E and 19E, which are described in section X of the present disclosure.

Some embodiments relate to a method of imaging a target object using a device, the method comprising: transmitting a first RF signal having a frequency component in a frequency band of 300GHz to 3THz, the frequency band having at least a first sub-frequency band and a second sub-frequency band; receiving a second RF signal generated by reflection of the first RF signal from the target object; and generating a multi-channel image having a first channel and a second channel, wherein data in the first channel is determined using frequency components of a first RF signal in a first sub-band, and wherein data in the second channel is determined using frequency components of a second RF waveform in a second sub-band. In some embodiments, the frequency band has a bandwidth of 10GHz to 60 GHz. In some embodiments, the first sub-band has a bandwidth of 2GHz to 20GHz (e.g., 4GHz to 8 GHz). In some embodiments, the method further includes determining a state (e.g., position) of the target object using the multi-channel image. In some embodiments, the method further comprises: assigning a first color to data in a first channel; and assigning a second color to the data in the second channel. It may include merging data in a first channel having a first color assigned thereto with data in a second channel having a second color assigned thereto.

IX. distance dependent integration

The present inventors have developed techniques for pulse integration in a distance dependent manner. Pulse wave integration is a technique for improving SNR in RADAR systems. Coherent integration involves sampling returns from pulses and summing the returns in phase with each other. Non-coherent integration involves sampling the returns from the pulses without regard to phase differences and adding the returns to each other.

The inventors have appreciated that objects located relatively close to the conveyor result in a higher SNR than objects located further from the conveyor. The signal resulting from the reflection from the closer object travels a shorter distance and thus experiences low propagation loss. In contrast, signals generated by reflection from more distant objects travel longer distances and thus experience large propagation losses. Integration techniques developed by the inventors involve integrating pulses corresponding to a far object at a higher rate than integrating pulses corresponding to a near object. Distance-dependent integration techniques developed by the present inventors and described herein involve a tradeoff between SNR and time resolution. The use of a higher integration rate images the farther object resulting in a smaller number of frames per second. For these objects, the SNR is improved, but the temporal resolution is reduced. However, the loss of time resolution may not be so detrimental as objects located far from the conveyor tend to appear as slow movements. In contrast, objects located closer to the conveyor appear with faster movement, and for such objects, time resolution is more important. Thus, a closer object is imaged using a lower integration rate, resulting in a greater number of frames per second.

According to some embodiments, an example of a system for performing distance-dependent integration is depicted in fig. 16A-16F. Fig. 16A illustrates a THz-based sensing system with TX antenna array 102 and RX antenna array 104. TX antenna array 102 transmits a plurality of pulses. According to some embodiments, one example of a pulse is illustrated in fig. 16B. In this example, the pulses are chirped-modulated with a carrier having a time-varying frequency. In other embodiments, other types of pulses may be transmitted. After the transmission pulse is reflected from the target object 500, a response pulse is generated. The RX antenna array 104 receives the response pulse. Each reply pulse carries information about the reflected power over each range. Fig. 16C is a plot illustrating the power received at the receiver in response to the transmission of the first pulse. The power is plotted as a function of distance. The x-axis is discretized in distance bins, and each distance bin represents a distance interval. In this example, the received power peaks correspond to 20m to 40m range bins and, likewise, 140m to 160m range bins. This behavior indicates that there may be an object located between 20m and 40m from the conveyor, and there may be another object located between 140m and 160m from the conveyor.

Fig. 16D is a plot illustrating power received at the receiver in response to the transmission of the second pulse, and 16E is a plot illustrating power received at the receiver in response to the transmission of the third pulse. In these examples, the response remains substantially unchanged, meaning that the object is significantly moving in the transmission of three pulses.

Recognizing that propagation loss increases with distance, the rates at which data corresponding to different response pulses can be determined as a function of distance basket are added to each other. Fig. 16F illustrates how the rate of integration may vary with distance according to some embodiments. In this example, each range bin is assigned a different integration rate (although in other examples, an integration rate may be assigned to more than one range). For example, a range bin corresponding to a distance in the interval 20m to 40m is assigned a rate of 2 integrations per second, and a range bin corresponding to a distance in the interval 140m to 160m is assigned a rate of 500 integrations per second. The results were: the frame rate at which the imaging data is located also varies with the distance. Fig. 16G illustrates that the frame rate may vary with distance according to some embodiments. In this example, a distance bin corresponding to a distance of 20m to 40m interval is associated with a frame rate of 500 Frames Per Second (FPS), and a distance bin corresponding to a distance of 140m to 160m interval is associated with a frame rate of 2 FPS. In some embodiments, integration may be performed in a coherent fashion, thereby increasing the SNR by a factor equal to the rate of integration.

The distance basket of fig. 16C to 16G has a width of 20 m. However, in other embodiments, the distance basket may have any suitable width. Furthermore, the width of the distance basket may be constant or may vary across the distance basket. In one example, one distance basket spans an interval of 0 to 25m, one distance basket spans an interval of 25 to 50m, one distance basket spans an interval of 50 to 100m, one distance basket spans an interval of 100 to 200m, one distance basket spans an interval of 200 to 300m, and one distance basket spans a value exceeding 300 m.

Some embodiments relate to a method of imaging a target object using a device, the method comprising: transmitting a first plurality of Radio Frequency (RF) pulses; receiving a second plurality of RF pulses resulting from reflections of the first plurality of pulses from the target object; and generating a plurality of images by integrating data obtained from the second plurality of RF pulses, wherein integrating the data comprises integrating data in different range bins using different integration rates, the integration rates of range bins in different range bins being set based on the distances associated with the range bins. In some embodiments, the method further includes setting a first rate corresponding to the first range bin and a second rate corresponding to the second range bin, wherein the first range bin represents at least a first distance and the second range bin represents at least a second distance less than the first distance, and wherein the first rate is less than the second rate, and the method further includes integrating data in the first range bin using the first rate and integrating data in the second range bin using the second rate. In some embodiments, integrating the data in the different range bins includes coherently integrating the data in the different range bins. In some embodiments, at least one pulse of the first plurality of pulses has a bandwidth of 10GHz to 60 GHz. In some embodiments, at least one pulse of the first plurality of pulses has a duration of 0.1ms to 10ms (e.g., 0.5ms to 2 ms).

X-ray measurement results

The inventors have performed various measurements using the devices and techniques described herein. Fig. 17A-17B are graphs illustrating signal-to-noise ratio versus distance in combination with two ranging measurements in accordance with some embodiments of the techniques described herein. Measurements corresponding to the plot of fig. 17A were performed using a target object positioned 124 cm from the THz ranging system and 30 degrees from the boresight of the TX antenna array. The signal has a carrier frequency between 660GHz and 680GHz and is modulated according to a 1ms chirp frequency. Further, coherent integration was applied by 1000 averages. As shown in the figure, the measured spectrum exhibited SNR peaks corresponding to a distance of approximately 43dB for 24 cm. This means that the THz ranging system 1 properly determines the location of the target object. In this example, the receiver has a noise figure of 47.4 dB.

Measurements corresponding to the plot of fig. 17B were also performed using a target object positioned 124 cm from the THz ranging system, but 55 degrees from the boresight of the TX antenna array. The signal has a carrier frequency between 700GHz and 720GHz and is modulated according to a 1ms chirp frequency. Further, coherent integration was applied by 1000 averages. As shown in the figure, the measured spectrum exhibits an SNR peak of approximately 48dB corresponding to a distance of 24cm, thereby indicating that the THz ranging system 1 properly determines the location of the target object. In this example, the receiver has a noise figure of 42 dB.

The present inventors further perform ranging-cross full-range measurements using the multi-dimensional imaging techniques and multi-channel imaging techniques described herein. Fig. 18A is a photograph of an arrangement for performing distance-cross full-distance measurement. The setup includes a THz ranging system 1 and a plurality of target objects (1800, 1802, and 1804). Article 1800 is shaped as a cylinder, article 1802 is shaped as a rod, and article 1804 is shaped as a base having a rod comb extending therefrom. All the objects are made of metal. Fig. 18B-18D are plots illustrating range-cross-over full-range measurements performed at different frequency ranges in accordance with the multi-channel imaging technique described in connection with fig. 15 and in connection with the setup of fig. 18A. Thus, the available frequency band is segmented into three sub-bands. As can be appreciated from fig. 18B-18D, all objects exhibit substantially the same response at each sub-band, indicating that these objects have a white response (non-frequency dependent response in the band of interest). This is consistent with the fact that all objects are made of the same material (metal). Fig. 18E is a plot illustrating a distance-cross full-distance measurement obtained by assigning colors to the measurements of fig. 18B-18D (red, green, and blue, respectively) and by summing the measurements together. As can be appreciated from fig. 18E, the THz ranging system 1 is able to properly image the target object.

In other cases, different target objects may exhibit different responses in the sub-bands, particularly for target objects made of different materials. To test this proposal, the inventors have performed measurements using complex target objects of the type that may be encountered on roads, for example. Fig. 19A is a photograph of an arrangement for performing distance-cross full-distance measurement. This arrangement includes THz ranging system 1 (not shown in fig. 19A), carrier 1900, bicycle 1902, and dummy 1904. Each of these articles is complex in that it includes various materials arranged in different shapes. The inventors have recognized that these types of target objects may benefit from the use of multi-channel imaging techniques of the type described herein. Consider, for example, that the edges of the vehicle are made of aluminum, the chassis is covered with paint, the tires are made of rubber, the head lamp is made of plastic, the windshield is made of glass, etc. While metals exhibit a substantially white response, other materials may reflect THz signals according to different frequency responses.

Fig. 19B-19D are plots illustrating range-cross-over full-range measurements performed at different frequency ranges in accordance with the multi-channel imaging technique described in connection with fig. 15 and in connection with the setup of fig. 19A. As can be appreciated from these figures, each sub-band highlights a different feature of the target object. Fig. 19E is a plot illustrating a distance-cross full-distance measurement obtained by assigning colors to the measurement results of fig. 19B-19D (red, green, and blue, respectively) and by summing the measurement results together. As can be appreciated from fig. 19E, the combined image is much richer than the images corresponding to the individual subbands.

XI example concept

1. A device, comprising: a substrate defining a plane extending in a first direction and a second direction substantially orthogonal to each other; a first Radio Frequency (RF) antenna array mounted on the substrate and having a first aperture with a first width extending in a first direction and a first length extending in a second direction, the first length being greater than the first width; and a second RF antenna array mounted on the substrate and having a second aperture with a second width extending in the first direction and a second length extending in the second direction, the second length being less than the second width.

2. The apparatus of concept 1, further comprising: RF transmission circuitry coupled to the first RF antenna array and configured to cause the first RF antenna array to transmit a first RF signal for determining a distance to the target object; RF receive circuitry coupled to the second RF antenna array and configured to receive a second RF signal from the second RF antenna array, the second RF signal resulting from reflection of the first RF signal by the target object; and processing circuitry coupled to the RF receiving circuitry, the processing circuitry configured to determine a distance between the device and the target object.

3. The apparatus of concept 2, wherein the processing circuitry is further coupled to the RF transmission circuitry.

4. The apparatus of any of concepts 1-3, wherein the first RF antenna array includes a first plurality of antennas sized to transmit megahertz RF signals, wherein megahertz RF signals have frequency components in a frequency band of 300GHz to 3THz, and wherein the second RF antenna array includes a second plurality of antennas sized to receive megahertz RF signals.

5. The apparatus of concept 3, wherein the megahertz RF signal has a bandwidth in the range of 10GHz to 60 GHz.

6. The apparatus of any of concepts 3-4, wherein the first plurality of antennas comprises 4 to 128 antennas.

7. The apparatus of any of concepts 3-6, wherein the second plurality of antennas comprises 32 to 1024 antennas.

8. The apparatus of any one of concepts 3 through 7, further comprising: a first semiconductor die mounted on the substrate, the first semiconductor die comprising a first RF antenna array, wherein a first plurality of antennas are integrated on the first semiconductor die.

9. The apparatus of concept 8, further comprising: a second semiconductor die mounted on the substrate, the second semiconductor die including a second RF antenna array, a second plurality of antennas being integrated on the second semiconductor die.

10. The apparatus of concept 1, further comprising: a first semiconductor die mounted on the substrate, the first semiconductor die comprising a first RF antenna array comprising a first plurality of antennas integrated on the first semiconductor die, the first plurality of antennas sized to transmit megahertz RF signals having frequency components in the 300GHz to 3THz frequency band; and a second semiconductor die mounted on the substrate, the second semiconductor die including a second RF antenna array including a second plurality of antennas integrated on the second semiconductor die, the second plurality of antennas sized to receive megahertz RF signals having frequency components in the 300GHz to 3THz frequency band.

11. The apparatus of concept 9, wherein the first semiconductor die further comprises: transmission circuitry; and a first redistribution layer coupling the first plurality of antennas to the transmission circuitry.

12. The apparatus of concept 11, wherein the second semiconductor die further comprises: receiving circuitry; and a second redistribution layer coupling the second plurality of antennas to the receive circuitry.

13. The apparatus of any of concepts 10-12, wherein the first semiconductor die comprises a first semiconductor type and the second semiconductor die comprises a second semiconductor type different from the first semiconductor type.

14. The apparatus of concept 13, wherein the first semiconductor die comprises a III-V semiconductor.

15. The apparatus of concept 14, wherein the first semiconductor die comprises indium phosphide.

16. The apparatus of any of concepts 13-15, wherein the second semiconductor die comprises silicon.

17. The apparatus of concept 13, wherein the first semiconductor die comprises indium phosphide and the second semiconductor die comprises silicon.

18. The device of any one of concepts 1-17, wherein the first aperture has a length between 5mm and 5cm and a width between 0.1mm and 5 mm.

19. The device of any one of concepts 1-18, wherein the length of the second aperture is between 0.1mm and 5mm and the width of the second aperture is between 1cm and 18 cm.

20. The apparatus of any of concepts 1-19, wherein the first RF antenna array has a quasi-linear configuration.

21. The apparatus of any of concepts 1 through 20, wherein the second RF antenna array has a quasi-linear configuration.

22. The apparatus of any of concepts 1 through 21, wherein the first RF antenna array has a linear configuration.

23. The apparatus of any of concepts 1-22, wherein the second RF antenna array has a linear configuration.

24. The apparatus of any one of concepts 1 through 23, wherein: the first RF antenna array includes a first plurality of antennas sized to transmit RF signals having frequency components in a frequency band of 650 to 690GHz, and a first aperture sized such that the first RF antenna array has an angular field of view in a first direction of between 50 and 150 in the frequency band of 650 to 690 GHz.

25. The apparatus of any one of concepts 1 through 24, wherein: the first RF antenna array includes a first plurality of antennas sized to transmit RF signals having frequency components in a frequency band of 650 to 690GHz and a first aperture sized such that the first RF antenna array has an angular field of view in a second direction between 200 and 900 in the frequency band of 650 to 690 GHz.

26. The apparatus of any of concepts 2-25, further comprising signal generation circuitry configured to generate and provide reference signals to the first RF antenna array and to the RF receive circuitry.

27. The apparatus of concept 26, wherein the signal generation circuitry comprises: a signal generator configured to generate an initial RF signal; and up-conversion circuitry coupled to the signal generator, the up-conversion circuitry configured to generate a reference signal by up-converting the initial RF signal.

28. The apparatus of concept 27, wherein the up-conversion circuitry comprises a plurality of frequency multipliers for step up-converting the initial RF signal.

29. The apparatus of concept 27, further comprising: a first semiconductor die mounted on the substrate, wherein the first semiconductor die comprises at least a portion of the first RF antenna array and the frequency up-conversion circuitry, and wherein the signal generator is mounted on the substrate.

30. The apparatus of concept 27, wherein the signal generator is mounted on a substrate and the frequency boost conversion circuitry is mounted on the substrate.

31. The apparatus of any of concepts 27-30, wherein the initial RF signal has a time-varying center frequency.

32. The concept 30 apparatus wherein the time-varying center frequency of the initial RF signal varies linearly over time.

33. The apparatus of concept 30, wherein the time-varying center frequency of the initial RF signal varies non-linearly over time.

34. A device, comprising: a substrate; a first semiconductor die mounted on the substrate, the first semiconductor die having a Radio Frequency (RF) transmit antenna array integrated thereon; a second semiconductor die mounted on the substrate, the second semiconductor die having an RF receive antenna array integrated thereon; and signal generation circuitry mounted at least partially on the substrate, the signal generation circuitry coupled to the first semiconductor die and to the second semiconductor die.

35. The apparatus of concept 34, wherein the signal generation circuitry comprises: an oscillator configured to generate a first signal; a signal generator configured to generate a second signal having a time-varying center frequency by frequency modulating the first signal; and up-conversion circuitry configured to generate a third signal by up-converting the second signal.

36. The apparatus of concept 35, wherein the first signal has a center frequency in the range of 1GHz to 20GHz, and wherein the up-conversion circuitry is configured to up-convert the second signal by a factor between 30 and 80.

37. The apparatus of concept 35, wherein the time-varying center frequency of the second signal varies linearly over time.

38. The apparatus of concept 35, wherein the time-varying center frequency of the second signal varies non-linearly over time.

39. The apparatus of concept 35, wherein the oscillator and the signal generator are mounted on a substrate and the first portion of the up-conversion circuitry is integrated on the first semiconductor die.

40. The apparatus of concept 39, wherein the second portion of the boost frequency conversion circuitry is mounted on the substrate.

41. The apparatus of concept 35, wherein the up-conversion circuitry comprises: a first plurality of frequency multipliers coupled to the RF transmit antenna array, wherein the first plurality of frequency multipliers is configured to upconvert respective input signals by a frequency multiplication factor; and a second plurality of frequency multipliers coupled to the RF receive antenna array, wherein the second plurality of multipliers is configured to upconvert the respective input signals by the frequency multiplication factor.

42. The apparatus of concept 41, wherein the first plurality of frequency multipliers is integrated on a first semiconductor die and the second plurality of multipliers is integrated on a second semiconductor die.

43. The apparatus of concept 42, wherein the first plurality of frequency multipliers and the second plurality of frequency multipliers are mounted on a substrate.

44. The apparatus of concept 35, wherein the signal generation circuitry further comprises a power divider and the frequency boost conversion circuitry comprises a plurality of frequency multipliers, wherein the power divider is configured to provide the second signal to at least some of the plurality of frequency multipliers.

45. The apparatus of concept 44, wherein the frequency multipliers are coupled to respective antennas in the transmit RF antenna array, and wherein the power divider is configured such that the antennas in the RF transmit antenna array transmit RF signals in phase with respect to each other.

46. The apparatus of concept 35, wherein the frequency multipliers are coupled to respective antennas in the transmit RF antenna array, and wherein the signal generation circuitry further comprises a plurality of phase shifters configured to cause antennas in the RF transmit antenna array to transmit RF signals in phase with respect to each other.

47. The apparatus of concept 44, wherein the plurality of frequency multipliers comprises a plurality of harmonic frequency multipliers.

48. The apparatus of any one of concepts 34 to 44, wherein the RF transmit antenna array comprises a plurality of RF antennas configured to transmit RF signals having frequency components in a frequency band of 300GHz to 3 THz.

49. A device, comprising: a substrate; a first semiconductor die mounted on the substrate, the first semiconductor die having a Radio Frequency (RF) transmit antenna array integrated thereon, the transmit antenna array comprising a first plurality of RF antennas sized to transmit a first RF signal having a frequency component in a frequency band of 300GHz to 3 THz; and a second semiconductor die mounted on the substrate, the second semiconductor die having an RF receive antenna array integrated thereon, the receive antenna array including a second plurality of RF antennas sized to receive a second RF signal having a frequency component in the frequency band.

50. The apparatus of concept 49, wherein an antenna of the first plurality of RF antennas is sized to transmit the first RF signal having a frequency component in a frequency band of 650 to 690 GHz.

51. The apparatus of any of concepts 49-50, further comprising signal generation circuitry configured to generate reference signals having a bandwidth of 10GHz to 60GHz and provide the signals to an RF transmit antenna array, wherein the RF transmit antenna array is configured to transmit the first RF signal in response to receiving the reference signals from the signal generation circuitry.

52. The apparatus of any of concepts 49 through 50, wherein the first RF antenna array has a bandwidth of 10GHz to 60 GHz.

53. The apparatus of any of concepts 49-52, wherein the first semiconductor die further comprises: RF transmission circuitry coupled to the RF transmission antenna array and configured to cause the RF transmission antenna array to transmit a first RF signal; and a redistribution layer coupling the first plurality of RF antennas to the transmission circuitry.

54. The apparatus of any of concepts 49-53, further comprising processing circuitry coupled to the RF receive antenna array and configured to determine a distance between the apparatus and the target object using the second RF signal.

55. The apparatus of concept 54, wherein the processing circuitry is further coupled to an RF transmit antenna array.

56. The apparatus of any of concepts 49-55, wherein the substrate defines a plane extending in a first direction and a second direction that are substantially orthogonal to each other, and wherein the RF transmit antenna array is configured to transmit the first RF signal in a third direction out of the plane.

57. The apparatus of any one of concepts 49 through 56, wherein the third direction is substantially perpendicular to the plane.

58. The apparatus of any of concepts 49-57, wherein the second plurality of RF antennas is configured to generate a differential signal in response to receiving the second RF signal.

59. The apparatus of any of concepts 49-58, wherein the second semiconductor die further comprises: a plurality of analog-to-digital converters (ADCs) coupled to the second plurality of RF antennas, the plurality of ADCs configured to digitize a third RF signal generated by the second plurality of RF antennas in response to receiving the second RF signal.

60. The apparatus of any of concepts 51-59, wherein the second semiconductor die further comprises a plurality of subharmonic mixers coupled to the second plurality of RF antennas and the plurality of ADCs, the subharmonic mixers configured to generate output signals by mixing the second RF signals with reference signals generated by the signal generation circuitry and to provide the output signals to the plurality of ADCs.

61. The apparatus of concept 60, wherein the plurality of subharmonic mixers comprises a plurality of third harmonic mixers configured to mix the second RF signal with third harmonics of the plurality of reference signals.

62. The apparatus of concept 60, wherein the plurality of subharmonic mixers comprises differential inputs coupled to respective RF antennas of the second plurality of antennas.

63. The apparatus of concept 62, wherein the plurality of subharmonic mixers further comprises a single-ended input configured to receive a reference signal generated by the signal generation circuitry.

64. The apparatus of concept 60, wherein the second semiconductor die further comprises a plurality of down-conversion mixers positioned between the plurality of subharmonic mixers and the plurality of ADCs, wherein the down-conversion mixers are configured to mix the output signal with a reference signal generated by the signal generation circuitry.

65. A device, comprising: a substrate; a first semiconductor die of a first semiconductor type mounted on the substrate, the first semiconductor die having a Radio Frequency (RF) transmit antenna array thereon; and a second semiconductor die of a second semiconductor type mounted on the substrate, the second semiconductor die having an RF receive antenna array thereon, wherein the second semiconductor type is different from the first semiconductor type.

66. The apparatus of concept 65, wherein the second semiconductor type is a silicon-based semiconductor type and the first semiconductor type is not a silicon-based semiconductor type.

67. The apparatus of concept 66, wherein the first semiconductor type is a III-V semiconductor type.

68. The apparatus of any of concepts 66-67, wherein the first semiconductor type is an indium phosphide (InP) semiconductor type.

69. The apparatus of any of concepts 65-68, wherein the second type is CMOS compatible.

70. The apparatus of any one of concepts 65 through 69, wherein the second semiconductor type is a silicon/germanium-based semiconductor type.

71. The device of any of concepts 65-70, wherein the first semiconductor type has an electron mobility between 3000cm ²V^{- 1}s^-1 and 5500cm ²V^-1s^-1 at 300K.

72. The apparatus of any of concepts 65-71, wherein the first semiconductor type has a current gain cutoff frequency (f _t) between 0.3THz and 1 THz.

73. The apparatus of any of concepts 65-72, wherein the first semiconductor type has a maximum oscillation frequency (f _max) between 0.7THz and 1.5 THz.

74. The apparatus of any of concepts 65 through 73, wherein the first semiconductor type has a breakdown electric field (Ebd) between 4 x 10 ⁵Vcm^-1 and 6 x 10 ⁵Vcm^-1.

75. The apparatus of any one of concepts 65 to 74, further comprising processing circuitry coupled to the RF transmit antenna array and to the RF receive antenna array and configured to determine a distance between the apparatus and the target object.

76. The apparatus of any of concepts 65-75, wherein the RF transmit antenna array comprises a plurality of RF antennas, and wherein the apparatus further comprises signal generation circuitry configured to generate the first signal and a power divider configured to provide the first signal to the first plurality of RF antennas.

77. The apparatus of concept 76, wherein the power divider is configured to provide the first signal having the same phase to the first plurality of RF antennas.

78. The apparatus of any of concepts 65-75, wherein the RF transmit antenna array comprises a plurality of antennas, and wherein the apparatus further comprises signal generation circuitry configured to generate the first signal and a plurality of phase shifters configured to provide the first signal having the same phase to the first plurality of RF antennas.

79. The apparatus of any one of concepts 65-78, wherein the RF transmit antenna array is sized to transmit RF signals in a frequency band of 300GHz to 3 THz.

80. The apparatus of concept 79, wherein the RF transmit antenna array is configured to transmit RF signals in the frequency band at a power level in the range of 10dBm to 30 dBm.

81. A device, comprising: a substrate; a first semiconductor die mounted on the substrate, the first semiconductor die having a Radio Frequency (RF) transmit antenna array integrated thereon; a second semiconductor die mounted on the substrate, the second semiconductor die having an RF receive antenna array integrated thereon; and a focusing element mounted on the substrate and configured to focus RF signals toward the RF receive antenna array.

82. The apparatus of concept 81, wherein the focusing element is transparent in a frequency band of 300GHz to 3 THz.

83. The apparatus of any one of concepts 81 to 82, wherein the focusing element is configured to focus RF signals having frequency components in a frequency band of 300GHz to 3THz toward the RF receive antenna array.

84. The apparatus of any of concepts 81-83, wherein the focusing element at least partially covers the RF receive antenna array and at least partially covers the RF transmit antenna array.

85. The apparatus of any of concepts 81-84, wherein the focusing element is a first focusing element at least partially covering the RF receive antenna array, and wherein the apparatus further comprises a second focusing element at least partially covering the RF transmit antenna array.

86. The apparatus of any one of concepts 81 to 85, wherein the focusing element comprises a cylindrical lens having a principal axis extending parallel to the first axis.

87. The apparatus of concept 86, wherein the RF receive antenna array has an aperture having a width extending parallel to the first axis and a length extending parallel to a second axis substantially orthogonal to the first axis, the width being greater than the length.

88. The apparatus of any one of concepts 81 through 87, wherein the focusing element is formed of silicon.

89. The apparatus of any one of concepts 81 to 85, wherein the focusing element comprises a spherical or elliptical lens.

90. A device, comprising: a substrate; a Radio Frequency (RF) transmit antenna array mounted on the substrate and configured to transmit a first RF signal having a power level between 10dBm and 30dBm, the first RF signal having a frequency component in a frequency band of 300GHz to 3 THz; an RF receive antenna array mounted on the substrate and configured to receive a second RF signal generated by reflection of the first RF signal from a target object; and processing circuitry coupled to the RF transmit antenna array and to the RF receive antenna array, the processing circuitry configured to determine a distance of the target object relative to the device using the second RF signal, wherein the processing circuitry has a Noise Figure (NF) of between 10dB and 40 dB.

91. The apparatus of concept 90, wherein the processing circuitry is configured to determine a distance between 1m and 200m at 60% humidity.

92. The apparatus of concept 90, wherein the RF transmission array has a bandwidth of 15GHz to 25GHz and a distance resolution of between 6mm and 10 mm.

93. The apparatus of any of concepts 90-92 wherein the RF transmit antenna array has an aperture between 1cm ² and 5cm ² and an angular resolution between 0.4 ° and 1 ° in the frequency band.

94. The device of any one of concepts 90-93, wherein the substrate has an area between 10cm ² and 60cm ².

95. The apparatus of any of concepts 90-94, wherein the processing circuitry is configured to update the determination of distance at a refresh rate between 0.1Hz and 100 Hz.

96. The apparatus of any one of concepts 90 through 95, further comprising: a first semiconductor die mounted on the substrate, the first semiconductor die including the RF transmit antenna array, the RF transmit antenna array including a first plurality of antennas integrated on the first semiconductor die.

97. The apparatus of any one of concepts 90 through 96, further comprising: a second semiconductor die mounted on the substrate, the second semiconductor die including the RF receive antenna array including a second plurality of antennas integrated on the second semiconductor die.

98. The apparatus of any one of concepts 90 through 97, further comprising: a first semiconductor die mounted on the substrate, the first semiconductor die comprising an RF transmit antenna array comprising a first plurality of antennas integrated on the first semiconductor die; and a second semiconductor die mounted on the substrate, the second semiconductor die including an RF receive antenna array including a second plurality of antennas integrated on the second semiconductor die.

99. The apparatus of concept 98, wherein the first semiconductor die comprises indium phosphide and the second semiconductor die comprises silicon.

100. The apparatus of any of concepts 90-99, wherein the RF transmit antenna array comprises a first linear antenna array.

101. The apparatus of concept 100, wherein the first linear antenna array comprises 4 to 128 antennas.

102. The apparatus of any of concepts 90-101, wherein the RF receive antenna array comprises a second linear antenna array.

103. The apparatus of concept 102, wherein the second linear antenna array comprises 32 to 1024 antennas.

104. The apparatus of any of concepts 90-103, wherein the RF transmit antenna array comprises a plurality of transmit antennas, each transmit antenna configured to transmit electromagnetic energy having a power level in the frequency band of between 1dBm and 2 dBm.

105. The apparatus of any of concepts 90-104, further comprising a focusing element mounted on the substrate and configured to focus a portion of the second RF signal to the RF receive antenna array.

106. The apparatus of any of concepts 90-105, wherein the first RF signal comprises pulses having a duration between 0.1ms and 10 ms.

107. The apparatus of any of concepts 90-106 wherein the RF transmit antenna array has a gain of between 3 and 20 dB.

108. A method of imaging a target object using an apparatus comprising a Radio Frequency (RF) transmit antenna array and an RF receive antenna array, the RF transmit antenna array having a first plurality of transmit antennas and a second plurality of transmit antennas, the method comprising: transmitting a first RF signal having a frequency component in a frequency band of 300GHz to 3THz using a first plurality of antennas; transmitting a second RF signal having a frequency component in the frequency band using a second plurality of antennas; generating a first image at least in part by receiving a third RF signal generated by reflection of the first RF signal from the target object using the RF receive antenna array; generating a second image at least in part by receiving a fourth RF signal generated by reflection of the second RF signal from the target object using the receive antenna array; and determining a state of the target object using the first image and the second image.

109. The method of concept 108, wherein the first RF signal has a frequency component in a frequency band of 650GHz to 690 GHz.

110. The method of any of concepts 108-109, wherein transmitting the second RF signal is performed after transmitting the first RF signal.

111. The method of any one of concepts 108 to 110, wherein: generating the first image includes determining a phase of the third RF signal; generating the second image includes determining a phase of the fourth RF signal; and determining the state of the target object includes determining a difference between the phase of the third RF signal and the phase of the fourth RF signal.

112. The method of any of concepts 108-111 wherein the transmit antenna array is oriented in a first direction and the receive antenna array is oriented in a second direction perpendicular to the first direction.

113. The method of any of concepts 108-112, wherein determining the state of the target object includes determining a position of the target object relative to the device.

114. A method of imaging a target object using a device, the method comprising: transmitting a first plurality of Radio Frequency (RF) pulses; receiving a second plurality of RF pulses resulting from reflections of the first plurality of pulses from the target object; and generating a plurality of images by integrating data obtained from the second plurality of RF pulses, wherein integrating the data comprises integrating data in different range bins using different integration rates, the integration rates of range bins in different range bins being set based on the distances associated with the range bins.

115. The method of concept 114, further comprising setting a first rate corresponding to a first distance bin and a second rate corresponding to a second distance bin, wherein the first distance bin represents at least a first distance and the second distance bin represents at least a second distance less than the first distance, and wherein the first rate is less than the second rate, and the method further comprises integrating data in the first distance bin using the first rate and integrating data in the second distance bin using the second rate.

116. The method of any of concepts 114-115, wherein integrating data in different range bins comprises integrating data in different range bins coherently.

117. The method of any of concepts 114-116, wherein at least one pulse of the first plurality of pulses has a bandwidth of 10GHz to 60 GHz.

118. The method of any of concepts 114-117, wherein at least one pulse of the first plurality of pulses has a duration of 0.1ms to 10 ms.

119. A method of imaging a target object using a device, the method comprising:

Transmitting a first Radio Frequency (RF) signal having a frequency component in a frequency band of 300GHz to 3THz, the frequency band having at least a first sub-band and a second sub-band; receiving a second RF signal generated by reflection of the first RF signal from the target object; and generating a multi-channel image having a first channel and a second channel, wherein data in the first channel is determined using frequency components of a first RF signal in a first sub-band, and wherein data in the second channel is determined using frequency components of a second RF waveform in a second sub-band.

120. The method of concept 119, wherein the frequency band has a bandwidth of 10GHz to 60 GHz.

121. The method of any of concepts 119-120, wherein the first sub-band has a bandwidth of 2GHz to 20 GHz.

122. The method of any one of concepts 119-121, further comprising determining a state of the target object using the multi-channel image.

123. The method of any one of concepts 119-122, further comprising: assigning a first color to data in a first channel; and assigning a second color to the data in the second channel, wherein generating the multi-channel image includes merging the data in the first channel having the first color assigned thereto with the data in the second channel having the second color assigned thereto.

124. A method of determining a distance between a device and a target object, the device including RF transmit circuitry coupled to a first Radio Frequency (RF) antenna array and RF receive circuitry coupled to a second RF antenna array, the device defining planes extending in first and second directions that are substantially orthogonal to each other, the method comprising: controlling the RF transmission circuitry to cause a first RF antenna array to transmit a first RF signal in a direction out of the plane of the device, wherein the first RF antenna array has a first aperture having a first width extending in a first direction and a first length extending in a second direction, the first length being greater than the first width; receiving a second RF signal due to reflection of the first RF signal from the target object using a second RF antenna array, wherein the second RF antenna array has a second aperture having a second width extending in the first direction and a second length extending in the second direction, the second length being less than the second width; and control processing circuitry coupled to the RF receive circuitry to determine a distance between the device and the target object.

125. The method of concept 124, wherein the RF signal has a frequency component in a frequency band of 300GHz to 3 THz.

126. The method of concept 124, wherein controlling the RF transmission circuitry such that the first RF antenna array transmits the first RF signal comprises generating a reference signal, and wherein receiving the second RF signal using the second RF antenna array comprises providing the reference signal to the second RF antenna array.

127. A method of manufacturing a device, comprising: obtaining a first semiconductor die of a first semiconductor type and patterned by a Radio Frequency (RF) transmission antenna array; obtaining a second semiconductor die of a second semiconductor type and patterned by the RF receive antenna array, the second semiconductor type being different from the first semiconductor type; and at least partially placing the first semiconductor die and the second semiconductor die on a substrate.

128. The method of concept 127, wherein the second semiconductor type is a silicon-based semiconductor type and the first semiconductor type is a III-V semiconductor type.

129. The method of concept 127, further comprising attaching a focusing element to the substrate such that the focusing element covers at least a portion of the RF receive antenna array.

130. The method of concept 127, further comprising: patterning the substrate with an RF power splitter having an input and a plurality of outputs prior to placing the first semiconductor die on the substrate; and after the first semiconductor die is placed on the substrate, coupling the output of the RF power splitter to respective ones of the RF transmission antennas via wire bonding.

131. A device, comprising: a substrate; an indium phosphide (InP) based die mounted on the substrate, the indium phosphide based die having a Radio Frequency (RF) transmit antenna array integrated thereon, wherein the RF transmit antenna array is sized to transmit RF signals in a frequency band of 300GHz to 3 THz; a silicon-based die mounted on the substrate, the silicon-based die having an RF receive antenna array integrated thereon; and processing circuitry coupled to the RF transmit antenna array and to the RF receive antenna array and configured to determine a distance between the device and the target object.

132. The apparatus of concept 131, further comprising transmit circuitry coupled to the RF transmit antenna array and configured to cause the RF transmit antenna array to transmit RF signals in a frequency band at a power level in a range of 10dBm to 30 dBm.

133. The apparatus of concept 131, wherein the RF transmit antenna array is sized to transmit RF signals in a frequency band of 650GHz to 690 GHz.

134. The apparatus of concept 131, further comprising: signal generation circuitry coupled to the transmit antenna array, the signal generation circuitry comprising up-conversion circuitry configured to receive an input signal having a first frequency and to generate an output signal having a second frequency that is a multiple of the first frequency; and receive circuitry coupled to the receive antenna array and to the signal generation circuitry.

135. The apparatus of concept 134, wherein the up-conversion circuitry comprises one or more diodes.

136. The apparatus of concept 134, wherein the receive circuitry comprises a harmonic mixer comprising a silicon-germanium (SiGe) Heterojunction Bipolar Transistor (HBT).

137. The apparatus of concept 131, wherein the RF transmit antenna array comprises 4 to 128 antennas and the receive antenna array comprises 32 to 1024 antennas.

138. A device for imaging a target object, comprising: a Radio Frequency (RF) transmission antenna configured to transmit a first RF signal having a frequency component in a frequency band of 300GHz to 3THz, the frequency band having at least a first sub-band and a second sub-band; an RF receive antenna configured to receive a second RF signal generated by reflection of the first RF signal from the target object; and processing circuitry configured to generate a multi-channel image having a first channel and a second channel, wherein the processing circuitry is configured to determine data in the first channel using frequency components of the second RF signal in the first sub-band and is configured to determine data in the second channel using frequency components of the second RF signal in the second sub-band.

139. The apparatus of concept 138, wherein the frequency band has a bandwidth of 10GHz to 60 GHz.

140. The apparatus of concept 138, wherein the frequency components are in a frequency band of 650GHz to 690 GHz.

141. The apparatus of concept 138, wherein the processing circuitry is further configured to determine a position of the target object relative to the apparatus using the multi-channel image.

142. The apparatus of concept 138, wherein the processing circuitry is further configured to: assigning a first color to data in a first channel; and assigning a second color to the data in the second channel, wherein generating the multi-channel image includes merging the data in the first channel having the first color assigned thereto with the data in the second channel having the second color assigned thereto.

143. The apparatus of concept 138, further comprising: a signal generator configured to generate an RF reference signal; and upconverting circuitry configured to upconvert the RF reference signal, wherein the processing circuitry is configured to generate the multichannel image by mixing the second RF signal with the upconverted RF reference signal.

144. The apparatus of concept 143, wherein the up-conversion circuitry is configured to up-convert the RF reference signal by a factor between 30 and 80.

145. The apparatus of concept 143, wherein the signal generator is configured to generate an RF reference signal to be chirped.

146. The apparatus of concept 138, wherein the frequency band further comprises a third sub-band, wherein the multi-channel image further comprises a third channel, and wherein the processing circuitry is further configured to determine data in the third channel using frequency components of the second RF signal in the third sub-band.

Having thus described several aspects of at least one embodiment of this technology, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art.

The above-described embodiments of the technology described herein may be implemented in any of numerous ways. For example, embodiments may be implemented using hardware, software, or a combination thereof. When implemented in software, the software codes may be executed on any suitable processor or collection of processors, whether provided in a single computer or distributed among multiple computers. Such processors may be implemented as integrated circuits, one or more processors in an integrated circuit component, including integrated circuit components known in the art as such as CPU chips, GPU chips, microprocessors, microcontrollers, or co-processors. In the alternative, the processor may be implemented in custom circuitry (such as an ASIC) or semi-custom circuitry generated by a configuration programmable logic device. As yet another alternative, the processor may be part of a larger circuit or semiconductor device, whether commercially available, semi-custom or custom made. As a particular example, some commercially available microprocessors have multiple cores, such that one or a subset of the cores may constitute the processor. However, the processor may be implemented using circuitry in any suitable format.

Also, the various methods or processes outlined herein may be coded as software that is executable on one or more processors to run any of a variety of operating systems or platforms. Such software may be written using any of several suitable programming languages and/or programming tools, including an instruction code processing language and/or instruction code processing tool. In some cases, such software may be compiled into executable machine language program code or intermediate program code that is executed on an architecture or virtual machine. Additionally or alternatively, such software may be interpreted.

The techniques disclosed herein may be implemented as a non-transitory computer-readable medium (or multiple computer-readable media) (e.g., a computer memory, one or more floppy discs, compact discs, optical discs, magnetic tapes, flash memories, circuit configurations in field programmable Gate arrays or other semiconductor devices, or other non-transitory tangible computer storage medium) encoded with one or more programs that, when executed on one or more processors, perform methods that implement the various embodiments of the invention described above. One or more computer-readable media may be transportable such that the one or more programs stored thereon can be loaded onto one or more different computers or other processors to implement various aspects of the present invention as described above.

The term "program" or "software" is used herein to refer to any type of computer program code or set of computer-executable instructions that can be used to program one or more processors to implement the various aspects of the present invention as described above. Furthermore, it should be appreciated that according to one aspect of this embodiment, one or more computer programs that, when executed, perform the methods of the present invention need not reside on a single computer or processor, but may be distributed in a modular fashion amongst a number of different computers or processors to implement various aspects of the present invention.

The various aspects of the techniques described herein may be used alone, in combination, or in a variety of configurations not specifically described in the embodiments described in the foregoing and are therefore not limited in their application to the details and configuration of components set forth in the foregoing description or illustrated in the drawings. For example, aspects described in one embodiment may be combined in any manner with aspects described in other embodiments.

Furthermore, the techniques described herein may be embodied as a method. Acts performed as part of a method may be ordered in any suitable manner. Thus, the following embodiments may be constructed: wherein the acts are performed in an order different from the order illustrated, i.e., may include performing some acts concurrently, even though such acts are shown as sequential acts in the illustrative embodiments.

As used in this specification and claims, the phrase "at least one" with respect to a list of one or more elements is understood to mean at least one element selected from any one or more of the elements in the list of elements, but does not necessarily include each and at least one of each element specifically listed within the list of elements, and does not necessarily exclude any combination of elements in the list of elements. This definition also allows that elements may optionally be present other than the specifically identified element in the list of elements referred to by the phrase "at least one," whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, "at least one of a and B" (or equivalently "at least one of a or B" or equivalently "at least one of a and/or B") may refer in one embodiment to at least one (optionally including more than one) a without B (and optionally including elements other than B); in another embodiment, at least one (optionally including more than one) B is meant without a (and optionally including elements other than a); in yet another embodiment, at least one (optionally including more than one) a and at least one (optionally including more than one) B (and optionally including other elements); etc.

As used in this specification and claims, the phrase "and/or" should be understood to mean "either or both" of the elements so combined, i.e., elements that in some cases exist in combination and in other cases exist in non-combination. The use of "and/or" of listed elements should be construed in the same manner, i.e., as "one or more" elements so combined. Other elements than those specifically identified by the "and/or" phrase, whether related or unrelated to those elements specifically identified, may optionally be present. Thus, as a non-limiting example, reference to "a and/or B", when used in conjunction with an open language such as "comprising", may in one embodiment refer to a alone (optionally including elements other than B); in another embodiment, it may refer to B only (optionally including elements other than a); in another embodiment, a and B (optionally including other elements) may be referred to; etc.

In the claims, the use of ordinal terms such as "first," "second," "third," etc., to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements.

Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having," "containing," "involving," and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.

Unless specified otherwise, the terms "substantially," "substantially," and "about" may be used to mean within ±10% of a target value in some embodiments. The terms "substantially", "essentially" and "about" may include target values.

Claims (146)

1. An apparatus, comprising:

A substrate defining a plane extending in a first direction and a second direction substantially orthogonal to each other;

a first Radio Frequency (RF) antenna array mounted on the substrate and having a first aperture with a first width extending in the first direction and a first length extending in the second direction, the first length being greater than the first width; and

A second RF antenna array mounted on the substrate and having a second aperture with a second width extending in the first direction and a second length extending in the second direction, the second length being less than the second width.

2. The apparatus according to claim 1, further comprising:

RF transmission circuitry coupled to the first RF antenna array and configured to cause the first RF antenna array to transmit a first RF signal for determining a distance to a target object;

RF receive circuitry coupled to the second RF antenna array and configured to receive a second RF signal from the second RF antenna array, the second RF signal resulting from reflection of the first RF signal by the target object; and

Processing circuitry coupled to the RF receive circuitry, the processing circuitry configured to determine a distance between the device and a target object.

3. The apparatus of claim 2, wherein the processing circuitry is further coupled to the RF transmission circuitry.

4. The device according to claim 1 to 3,

Wherein the first RF antenna array comprises a first plurality of antennas sized to transmit megahertz RF signals having frequency content in a frequency band of 300GHz to 3THz, an

Wherein the second RF antenna array includes a second plurality of antennas sized to receive megahertz RF signals.

5. The apparatus of claim 3, wherein the megahertz RF signal has a bandwidth in a range of 10GHz to 60 GHz.

6. The apparatus of any of claims 3 to 4, wherein the first plurality of antennas comprises 4 to 128 antennas.

7. The apparatus of any of claims 3 to 6, wherein the second plurality of antennas comprises 32 to 1024 antennas.

8. The apparatus according to any one of claims 3 to 7, further comprising:

A first semiconductor die mounted on the substrate, the first semiconductor die including the first RF antenna array, wherein the first plurality of antennas are integrated on the first semiconductor die.

9. The apparatus according to claim 8, further comprising:

a second semiconductor die mounted on the substrate, the second semiconductor die including the second RF antenna array, the second plurality of antennas being integrated on the second semiconductor die.

10. The apparatus according to claim 1, further comprising:

A first semiconductor die mounted on the substrate, the first semiconductor die including the first RF antenna array, the first RF antenna array including a first plurality of antennas integrated on the first semiconductor die, the first plurality of antennas sized to transmit megahertz RF signals having frequency components in the 300GHz to 3THz frequency band; and

A second semiconductor die mounted on the substrate, the second semiconductor die including the second RF antenna array, the second RF antenna array including a second plurality of antennas integrated on the second semiconductor die, the second plurality of antennas sized to receive megahertz RF signals having frequency components in the 300GHz to 3THz frequency band.

11. The apparatus of claim 9, wherein the first semiconductor die further comprises:

the transmission circuit system, and

A first redistribution layer coupling the first plurality of antennas to the transmission circuitry.

12. The apparatus of claim 11, wherein the second semiconductor die further comprises:

The receiving circuitry; and

A second redistribution layer coupling the second plurality of antennas to the receive circuitry.

13. The apparatus of any of claims 10 to 12, wherein the first semiconductor die comprises a first semiconductor type and the second semiconductor die comprises a second semiconductor type different from the first semiconductor type.

14. The apparatus of claim 13, wherein the first semiconductor die comprises a III-V semiconductor.

15. The apparatus of claim 14, wherein the first semiconductor die comprises indium phosphide.

16. The apparatus of any of claims 13 to 15, wherein the second semiconductor die comprises silicon.

17. The apparatus of claim 13, wherein the first semiconductor die comprises indium phosphide and the second semiconductor die comprises silicon.

18. The device of any one of claims 1 to 17, wherein the first aperture has a length of between 5mm and 5cm and a width of between 0.1mm and 5 mm.

19. The device of any one of claims 1 to 18, wherein the length of the second aperture is between 0.1mm and 5mm and the width of the second aperture is between 1cm and 18 cm.

20. The apparatus of any of claims 1 to 19, wherein the first RF antenna array has a quasi-linear configuration.

21. The apparatus of any of claims 1 to 20, wherein the second RF antenna array has a quasi-linear configuration.

22. The apparatus of any of claims 1 to 21, wherein the first RF antenna array has a linear configuration.

23. The apparatus of any of claims 1 to 22, wherein the second RF antenna array has a linear configuration.

24. The apparatus according to any one of claims 1 to 23, wherein:

The first RF antenna array includes a first plurality of antennas sized to transmit RF signals having frequency components in a frequency band of 650 to 690GHz, an

The first aperture is sized such that the first RF antenna array has an angular field of view in the first direction of between 50 and 150 in a frequency band of 650 to 690 GHz.

25. The apparatus according to any one of claims 1 to 24, wherein:

The first RF antenna array includes a first plurality of antennas sized to transmit RF signals having frequency components in a frequency band of 650 to 690GHz, an

The first aperture is sized such that the first RF antenna array has an angular field of view in the second direction of between 200 and 900 in a frequency band of 650 to 690 GHz.

26. The apparatus of any of claims 2 to 25, further comprising signal generation circuitry configured to generate a reference signal and provide the reference signal to the first RF antenna array and to the RF receive circuitry.

27. The apparatus of claim 26, wherein the signal generation circuitry comprises:

a signal generator configured to generate an initial RF signal; and

Frequency up-conversion circuitry coupled to the signal generator, the frequency up-conversion circuitry configured to generate the reference signal by frequency up-converting the initial RF signal.

28. The apparatus of claim 27, wherein the up-conversion circuitry comprises a plurality of frequency multipliers for step up-converting the initial RF signal.

29. The apparatus of claim 27, further comprising:

a first semiconductor die mounted on the substrate,

Wherein the first semiconductor die includes at least a portion of the first RF antenna array and the up-conversion circuitry, an

Wherein the signal generator is mounted on the substrate.

30. The apparatus of claim 27, wherein the signal generator is mounted on the substrate and the frequency up-conversion circuitry is mounted on the substrate.

31. The apparatus of any of claims 27 to 30, wherein the initial RF signal has a time-varying center frequency.

32. The apparatus of claim 30, wherein the time-varying center frequency of the initial RF signal varies linearly over time.

33. The apparatus of claim 30, wherein the time-varying center frequency of the initial RF signal varies non-linearly over time.

34. An apparatus, comprising:

A substrate;

a first semiconductor die mounted on the substrate, the first semiconductor die having a Radio Frequency (RF) transmit antenna array integrated thereon;

a second semiconductor die mounted on the substrate, the second semiconductor die having an RF receive antenna array integrated thereon; and

Signal generation circuitry mounted at least partially on the substrate, the signal generation circuitry coupled to the first semiconductor die and to the second semiconductor die.

35. The apparatus of claim 34, wherein the signal generation circuitry comprises:

An oscillator configured to generate a first signal;

a signal generator configured to generate a second signal having a time-varying center frequency by frequency modulating the first signal; and

Frequency up-conversion circuitry configured to generate a third signal by frequency up-converting the second signal.

36. An apparatus according to claim 35,

Wherein the first signal has a center frequency in the range of 1GHz to 20GHz, an

Wherein the up-conversion circuitry is configured to up-convert the second signal by a factor between 30 and 80.

37. The apparatus of claim 35, wherein the time-varying center frequency of the second signal varies linearly over time.

38. The apparatus of claim 35, wherein the time-varying center frequency of the second signal varies non-linearly over time.

39. The apparatus of claim 35, wherein the oscillator and the signal generator are mounted on the substrate and the first portion of the up-conversion circuitry is integrated on the first semiconductor die.

40. The apparatus of claim 39, wherein the second portion of the frequency boost conversion circuitry is mounted on the substrate.

41. The apparatus of claim 35, wherein the up-conversion circuitry comprises:

A first plurality of frequency multipliers coupled to the RF transmit antenna array, wherein the first plurality of frequency multipliers is configured to upconvert respective input signals by a frequency multiplication factor; and

A second plurality of frequency multipliers coupled to the RF receive antenna array, wherein the second plurality of multipliers is configured to upconvert respective input signals by the frequency multiplication factor.

42. The apparatus of claim 41, wherein the first plurality of frequency multipliers is integrated on the first semiconductor die and the second plurality of multipliers is integrated on the second semiconductor die.

43. The apparatus of claim 42, wherein the first plurality of frequency multipliers and the second plurality of frequency multipliers are mounted on the substrate.

44. The apparatus of claim 35, wherein the signal generation circuitry further comprises a power divider and the frequency boost conversion circuitry comprises a plurality of frequency multipliers, wherein the power divider is configured to provide the second signal to at least some of the plurality of frequency multipliers.

45. The apparatus of claim 44, wherein the plurality of frequency multipliers are coupled to respective antennas in the transmit RF antenna array, and wherein the power divider is configured such that the plurality of antennas in the RF transmit antenna array transmit RF signals in phase with respect to each other.

46. The apparatus of claim 35, wherein the plurality of frequency multipliers are coupled to respective antennas in the transmit RF antenna array, and wherein the signal generation circuitry further comprises a plurality of phase shifters configured to cause the plurality of antennas in the RF transmit antenna array to transmit RF signals in phase with respect to each other.

47. The apparatus of claim 44, wherein the plurality of frequency multipliers comprises a plurality of harmonic frequency multipliers.

48. The apparatus of any one of claims 34 to 44, wherein the RF transmit antenna array comprises a plurality of RF antennas configured to transmit RF signals having frequency components in a frequency band of 300GHz to 3 THz.

49. An apparatus, comprising:

A substrate;

A first semiconductor die mounted on the substrate, the first semiconductor die having a Radio Frequency (RF) transmit antenna array integrated thereon, the transmit antenna array comprising a first plurality of RF antennas sized to transmit a first RF signal having a frequency component in a frequency band of 300GHz to 3 THz; and

A second semiconductor die mounted on the substrate, the second semiconductor die having an RF receive antenna array integrated thereon, the receive antenna array including a second plurality of RF antennas sized to receive a second RF signal having a frequency component in the frequency band.

50. The apparatus of claim 49, wherein the plurality of antennas of the first plurality of RF antennas are sized to transmit the first RF signal having a frequency content in a frequency band of 650 to 690 GHz.

51. The apparatus of any one of claims 49 to 50, further comprising signal generation circuitry configured to generate a reference signal having a bandwidth of 10GHz to 60GHz and to provide the signal to the RF transmit antenna array, wherein the RF transmit antenna array is configured to transmit the first RF signal in response to receiving the reference signal from the signal generation circuitry.

52. The apparatus of any one of claims 49 to 50, wherein the first RF antenna array has a bandwidth of 10GHz to 60 GHz.

53. The apparatus of any one of claims 49 to 52, wherein the first semiconductor die further comprises:

RF transmission circuitry coupled to the RF transmission antenna array and configured to cause the RF transmission antenna array to transmit the first RF signal; and

A redistribution layer coupling the first plurality of RF antennas to the transmission circuitry.

54. The apparatus of any one of claims 49 to 53, further comprising processing circuitry coupled to the RF receive antenna array and configured to determine a distance between the apparatus and a target object using the second RF signal.

55. The apparatus of claim 54, wherein the processing circuitry is further coupled to the RF transmit antenna array.

56. The apparatus of any one of claims 49 to 55, wherein the substrate defines a plane extending in first and second directions orthogonal to each other, and wherein the RF transmit antenna array is configured to transmit the first RF signal in a third direction outside the plane.

57. The apparatus of any one of claims 49 to 56, wherein the third direction is substantially perpendicular to the plane.

58. The apparatus of any one of claims 49 to 57, wherein the second plurality of RF antennas is configured to generate a differential signal in response to receiving the second RF signal.

59. The apparatus of any one of claims 49 to 58, wherein the second semiconductor die further comprises:

A plurality of analog-to-digital converters (ADCs) coupled to the second plurality of RF antennas, the plurality of ADCs configured to digitize a third RF signal generated by the second plurality of RF antennas in response to receiving the second RF signal.

60. The apparatus of any one of claims 51 to 59, wherein the second semiconductor die further comprises a plurality of subharmonic mixers coupled to the second plurality of RF antennas and the plurality of ADCs, the plurality of subharmonic mixers configured to generate an output signal by mixing the second RF signal with the reference signal generated by the signal generation circuitry and to provide the output signal to the plurality of ADCs.

61. The apparatus of claim 60 wherein the plurality of subharmonic mixers comprises a plurality of third harmonic mixers configured to mix the second RF signal with third harmonics of the plurality of reference signals.

62. The apparatus of claim 60, wherein the plurality of subharmonic mixers comprises differential inputs coupled to respective RF antennas of the second plurality of antennas.

63. The apparatus of claim 62, wherein the plurality of subharmonic mixers further comprise a single-ended input configured to receive the reference signal generated by the signal generation circuitry.

64. The apparatus of claim 60, wherein the second semiconductor die further comprises a plurality of down-conversion mixers positioned between the plurality of subharmonic mixers and the plurality of ADCs, wherein the plurality of down-conversion mixers are configured to mix the output signal with the reference signal generated by the signal generation circuitry.

65. An apparatus, comprising:

A substrate;

a first semiconductor die of a first semiconductor type mounted on the substrate, the first semiconductor die having a Radio Frequency (RF) transmit antenna array thereon; and

A second semiconductor die of a second semiconductor type mounted on the substrate, the second semiconductor die having an RF receive antenna array thereon, wherein the second semiconductor type is different from the first semiconductor type.

66. The apparatus of claim 65, wherein the second semiconductor type is a silicon-based semiconductor type and the first semiconductor type is not a silicon-based semiconductor type.

67. The apparatus of claim 66, wherein the first semiconductor type is a III-V semiconductor type.

68. The device of any of claims 66 to 67, wherein the first semiconductor type is an indium phosphide (InP) semiconductor type.

69. The apparatus of any one of claims 65 to 68, wherein the second semiconductor type is CMOS compatible.

70. The apparatus of any one of claims 65 to 69, wherein the second semiconductor type is a silicon/germanium-based semiconductor type.

71. The device of any one of claims 65 to 70, wherein the first semiconductor type has an electron mobility at 300K between 3000cm ²V-1s^-1 and 5500cm ²V^-1s^-1.

72. The apparatus of any one of claims 65 to 71, wherein the first semiconductor type has a current gain cut-off frequency (f _t) between 0.3THz and 1 THz.

73. The apparatus of any one of claims 65 to 72, wherein the first semiconductor type has a maximum oscillation frequency (f _max) between 0.7THz and 1.5 THz.

74. The device of any of claims 65 to 73, wherein the first semiconductor type has a breakdown electric field (Ebd) between 4 x 10 ⁵Vcm^-1 and 6 x 10 ⁵Vcm^-1.

75. The apparatus of any one of claims 65 to 74, further comprising processing circuitry coupled to the RF transmit antenna array and to the RF receive antenna array and configured to determine a distance between the apparatus and a target object.

76. The apparatus of any one of claims 65 to 75, wherein the RF transmit antenna array comprises a plurality of RF antennas, and wherein the apparatus further comprises signal generation circuitry configured to generate a first signal and a power divider configured to provide the first signal to the first plurality of RF antennas.

77. The apparatus of claim 76, wherein the power divider is configured to provide the first signal having the same phase to the first plurality of RF antennas.

78. The apparatus of any one of claims 65 to 75, wherein the RF transmit antenna array comprises a plurality of antennas, and wherein the apparatus further comprises signal generation circuitry configured to generate a first signal and a plurality of phase shifters configured to provide the first signal having the same phase to the first plurality of RF antennas.

79. The apparatus of any one of claims 65 to 78, wherein the RF transmit antenna array is sized to transmit RF signals in a frequency band of 300GHz to 3 THz.

80. The apparatus of claim 79, wherein the RF transmit antenna array is configured to transmit the RF signals in the frequency band at a power level in the range of 10dBm to 30 dBm.

81. An apparatus, comprising:

A substrate;

a first semiconductor die mounted on the substrate, the first semiconductor die having a Radio Frequency (RF) transmit antenna array integrated thereon;

a second semiconductor die mounted on the substrate, the second semiconductor die having an RF receive antenna array integrated thereon; and

A focusing element mounted on the substrate and configured to focus RF signals toward the RF receive antenna array.

82. The apparatus of claim 81 wherein the focusing element is transparent in the frequency band of 300GHz to 3 THz.

83. The apparatus of any one of claims 81 to 82 wherein the focusing element is configured to focus RF signals having frequency components in a frequency band of 300GHz to 3THz towards the RF receive antenna array.

84. The apparatus of any one of claims 81 to 83, wherein the focusing element at least partially covers the RF receive antenna array and at least partially covers the RF transmit antenna array.

85. The apparatus of any one of claims 81 to 84 wherein the focusing element is a first focusing element at least partially covering the RF receive antenna array, and wherein the apparatus further comprises a second focusing element at least partially covering the RF transmit antenna array.

86. The apparatus of any one of claims 81 to 85, wherein the focusing element comprises a cylindrical lens having a principal axis extending parallel to the first axis.

87. The apparatus of claim 86, wherein the RF receive antenna array has an aperture having a width extending parallel to the first axis and a length extending parallel to a second axis substantially orthogonal to the first axis, the width being greater than the length.

88. The device of any one of claims 81 to 87, wherein the focusing element is formed of silicon.

89. The device of any one of claims 81 to 85 wherein the focussing element comprises a spherical or elliptical lens.

90. An apparatus, comprising:

The substrate is provided with a plurality of grooves,

A Radio Frequency (RF) transmit antenna array mounted on the substrate and configured to transmit a first RF signal having a power level between 10dBm and 30dBm, the first RF signal having a frequency component in a frequency band of 300GHz to 3 THz;

An RF receive antenna array mounted on the substrate and configured to receive a second RF signal generated by reflection of the first RF signal from a target object; and

Processing circuitry coupled to the RF transmit antenna array and to the RF receive antenna array, the processing circuitry configured to determine a distance of the target object relative to the device using the second RF signal, wherein the processing circuitry has a Noise Figure (NF) of between 10dB and 40 dB.

91. The apparatus of claim 90, wherein the processing circuitry is configured to determine a distance between 1m and 200m at 60% humidity.

92. The apparatus of any one of claims 90 to 91, wherein the RF transmission array has a bandwidth of 15GHz to 25GHz and a range resolution of between 6mm and 10 mm.

93. The apparatus of any one of claims 90 to 92, wherein the RF transmit antenna array has an aperture of between 1cm ² and 5cm ² and an angular resolution of between 0.4 ° and 1 ° in the frequency band.

94. The device of any one of claims 90 to 93, wherein the substrate has an area between 10cm ² and 60cm ².

95. The apparatus of any one of claims 90 to 94, wherein the processing circuitry is configured to update the determination of the distance at a refresh rate between 0.1Hz and 100 Hz.

96. The apparatus of any one of claims 90 to 95, further comprising:

A first semiconductor die mounted on the substrate, the first semiconductor die including the RF transmit antenna array, the RF transmit antenna array including a first plurality of antennas integrated on the first semiconductor die.

97. The apparatus of any one of claims 90 to 96, further comprising:

A second semiconductor die mounted on the substrate, the second semiconductor die including the RF receive antenna array, the RF receive antenna array including a second plurality of antennas integrated on the second semiconductor die.

98. The apparatus of any one of claims 90 to 97, further comprising:

A first semiconductor die mounted on the substrate, the first semiconductor die including the RF transmit antenna array, the RF transmit antenna array including a first plurality of antennas integrated on the first semiconductor die; and

A second semiconductor die mounted on the substrate, the second semiconductor die including the RF receive antenna array, the RF receive antenna array including a second plurality of antennas integrated on the second semiconductor die.

99. The apparatus of claim 98, wherein the first semiconductor die comprises indium phosphide and the second semiconductor die comprises silicon.

100. The apparatus of any one of claims 90 to 99, wherein the RF transmit antenna array comprises a first linear antenna array.

101. The apparatus of claim 100, wherein the first linear antenna array comprises 4 to 128 antennas.

102. The apparatus of any one of claims 90 to 101, wherein the RF receive antenna array comprises a second linear antenna array.

103. The apparatus of claim 102, wherein the second linear antenna array comprises 32 to 1024 antennas.

104. The apparatus of any one of claims 90 to 103, wherein the RF transmit antenna array comprises a plurality of transmit antennas, each transmit antenna configured to transmit electromagnetic energy having a power level in the frequency band of between 1dBm and 2 dBm.

105. The apparatus of any one of claims 90 to 104, further comprising a focusing element mounted on the substrate and configured to focus a portion of the second RF signal to the RF receive antenna array.

106. The apparatus of any one of claims 90 to 105, wherein the first RF signal comprises pulses having a duration between 0.1ms and 10 ms.

107. The apparatus of any one of claims 90 to 106, wherein the RF transmit antenna array has a gain of between 3 and 20 dB.

108. A method of imaging a target object using an apparatus comprising a Radio Frequency (RF) transmit antenna array and an RF receive antenna array, the RF transmit antenna array having a first plurality of transmit antennas and a second plurality of transmit antennas, the method comprising:

transmitting a first RF signal having a frequency component in a frequency band of 300GHz to 3THz using the first plurality of antennas;

transmitting a second RF signal having a frequency component in the frequency band using the second plurality of antennas;

generating a first image at least in part by receiving a third RF signal generated by reflection of the first RF signal from the target object using the RF receive antenna array;

generating a second image at least in part by receiving a fourth RF signal generated by reflection of the second RF signal from the target object using the receive antenna array; and

The state of the target object is determined using the first image and the second image.

109. The method of claim 108, wherein the first RF signal has a frequency component in a frequency band of 650GHz to 690 GHz.

110. The method of any one of claims 108 to 109, wherein transmitting the second RF signal is performed after transmitting the first RF signal.

111. The method of any one of claims 108 to 110, wherein:

Generating the first image includes determining a phase of the third RF signal;

generating the second image includes determining a phase of the fourth RF signal; and

Determining the state of the target object includes determining a difference between the phase of the third RF signal and the phase of the fourth RF signal.

112. The method of any one of claims 108 to 111, wherein the transmit antenna array is oriented in a first direction and the receive antenna array is oriented in a second direction perpendicular to the first direction.

113. The method of any one of claims 108 to 112, wherein determining the state of the target object comprises determining the position of the target object relative to the device.

114. A method of imaging a target object using a device, the method comprising:

Transmitting a first Radio Frequency (RF) signal having a frequency component in a frequency band of 300GHz to 3THz, the frequency band having at least a first sub-band and a second sub-band;

Receiving a second RF signal generated by reflection of the first RF signal from the target object; and

Generating a multi-channel image having a first channel and a second channel, wherein data in the first channel is determined using frequency components of the first RF signal in the first sub-band, and wherein data in the second channel is determined using frequency components of the second RF waveform in the second sub-band.

115. The method of claim 114, wherein the frequency band has a bandwidth of 10GHz to 60 GHz.

116. The method of claim 114 or 115, wherein the first sub-band has a bandwidth of 2GHz to 20 GHz.

117. The method of claim 114, further comprising determining a state of the target object using the multi-channel image.

118. A method according to claim 114, further comprising:

Assigning a first color to the data in the first channel; and

Assigning a second color to the data in the second channel,

Wherein generating the multi-channel image includes merging the data in the first channel having the first color assigned thereto with the data in the second channel having the second color assigned thereto.

119. A method of imaging a target object using a device, the method comprising:

transmitting a first plurality of Radio Frequency (RF) pulses;

Receiving a second plurality of RF pulses resulting from reflections of the first plurality of pulses from the target object; and

Generating a plurality of images by integrating data obtained from the second plurality of RF pulses, wherein integrating the data includes integrating the data in different range bins using different integration rates, the integration rates of range bins in the different range bins being set based on distances associated with the range bins.

120. The method of claim 119, further comprising setting a first rate corresponding to a first distance bin and a second rate corresponding to a second distance bin, wherein the first distance bin represents at least a first distance and the second distance bin represents at least a second distance less than the first distance, and wherein the first rate is less than the second rate, and

Wherein the method further comprises integrating the data in the first range bin using the first rate and integrating the data in the second range bin using the second rate.

121. The method of any of claims 119 to 120, wherein integrating the data in different range bins comprises integrating the data in different range bins coherently.

122. The method of any one of claims 119-121, wherein at least one pulse of the first plurality of pulses has a bandwidth of 10GHz to 60 GHz.

123. The method of any of claims 119-122, wherein at least one pulse of the first plurality of pulses has a duration of 0.1ms to 10 ms.

124. A method of determining a distance between a device and a target object, the device including RF transmit circuitry coupled to a first Radio Frequency (RF) antenna array and RF receive circuitry coupled to a second RF antenna array, the device defining planes extending in first and second directions that are substantially orthogonal to each other, the method comprising:

controlling the RF transmission circuitry to cause the first RF antenna array to transmit a first RF signal in a direction out of the plane of the device, wherein the first RF antenna array has a first aperture having a first width extending in the first direction and a first length extending in the second direction, the first length being greater than the first width;

receiving a second RF signal generated by reflection of the first RF signal from the target object using the second RF antenna array, wherein the second RF antenna array has a second aperture having a second width extending in the first direction and a second length extending in the second direction, the second length being less than the second width; and

Processing circuitry coupled to the RF receive circuitry is controlled to determine the distance between the device and the target object.

125. The method of claim 124, wherein the RF signal has a frequency component in a frequency band of 300GHz to 3 THz.

126. The method of any one of claims 124-125, wherein controlling the RF transmission circuitry such that the first RF antenna array transmits the first RF signal includes generating a reference signal, and wherein receiving the second RF signal using the second RF antenna array includes providing the reference signal to the second RF antenna array.

127. A method of manufacturing a device, comprising:

obtaining a first semiconductor die of a first semiconductor type and patterned by a Radio Frequency (RF) transmission antenna array;

obtaining a second semiconductor die of a second semiconductor type and patterned by the RF receive antenna array, the second semiconductor type being different from the first semiconductor type; and

The device is fabricated by at least partially disposing the first semiconductor die and the second semiconductor die on a substrate.

128. The method of claim 127, wherein the second semiconductor type is a silicon-based semiconductor type and the first semiconductor type is a III-V semiconductor type.

129. The method of any one of claims 127 to 128, further comprising attaching a focusing element to the substrate such that the focusing element covers at least a portion of the RF receive antenna array.

130. The method of any one of claims 127 to 129, further comprising:

Patterning the substrate with an RF power splitter having an input and a plurality of outputs prior to placing the first semiconductor die on the substrate; and

After the first semiconductor die is placed on the substrate, the output of the RF power divider is coupled to each of the RF transmit antennas via wire bonding.

131. An apparatus, comprising:

A substrate;

An indium phosphide (InP) based die mounted on the substrate, the indium phosphide based die having a Radio Frequency (RF) transmit antenna array integrated thereon, wherein the RF transmit antenna array is sized to transmit RF signals in a frequency band of 300GHz to 3 THz;

A silicon-based die mounted on the substrate, the silicon-based die having an RF receive antenna array integrated thereon; and

Processing circuitry coupled to the RF transmit antenna array and to the RF receive antenna array and configured to determine a distance between the device and a target object.

132. The apparatus of claim 131, further comprising transmit circuitry coupled to the RF transmit antenna array and configured to cause the RF transmit antenna array to transmit the RF signal in the frequency band at a power level in a range of 10dBm to 30 dBm.

133. The apparatus of any one of claims 131 to 132, wherein the RF transmit antenna array is sized to transmit the RF signal in a frequency band of 650GHz to 690 GHz.

134. The apparatus of any one of claims 131 to 133, further comprising:

Signal generation circuitry coupled to the transmit antenna array, the signal generation circuitry comprising up-conversion circuitry configured to receive an input signal having a first frequency and to generate an output signal having a second frequency that is a multiple of the first frequency; and

And receiving circuitry coupled to the receive antenna array and to the signal generation circuitry.

135. The apparatus of claim 134, wherein the frequency boost conversion circuitry includes one or more diodes.

136. The apparatus of claim 134, wherein the receive circuitry comprises a harmonic mixer comprising a silicon-germanium (SiGe) Heterojunction Bipolar Transistor (HBT).

137. The apparatus of any one of claims 131 to 136, wherein the RF transmit antenna array comprises 4 to 128 antennas and the receive antenna array comprises 32 to 1024 antennas.

138. A device for imaging a target object, comprising:

A Radio Frequency (RF) transmission antenna configured to transmit a first RF signal having a frequency component in a frequency band of 300GHz to 3THz, the frequency band having at least a first sub-band and a second sub-band;

an RF receive antenna configured to receive a second RF signal generated by reflection of the first RF signal from the target object; and

Processing circuitry configured to generate a multi-channel image having a first channel and a second channel, wherein the processing circuitry is configured to determine data in the first channel using frequency components of the second RF signal in the first sub-band and is configured to determine data in the second channel using frequency components of the second RF signal in the second sub-band.

139. The apparatus of claim 138, wherein the frequency band has a bandwidth of 10GHz to 60 GHz.

140. The apparatus of any one of claims 138 to 139, wherein the frequency component is in a frequency band of 650GHz to 690 GHz.

141. The apparatus of any one of claims 138 to 140, wherein the processing circuitry is further configured to determine a position of the target object relative to the apparatus using the multi-channel image.

142. The apparatus of any one of claims 138-141, wherein the processing circuitry is further configured to:

Assigning a first color to the data in the first channel, an

Assigning a second color to the data in the second channel,

Wherein generating the multi-channel image includes merging the data in the first channel having the first color assigned thereto with the data in the second channel having the second color assigned thereto.

143. The apparatus of any one of claims 138-142, further comprising:

A signal generator configured to generate an RF reference signal; and

Frequency up-conversion circuitry configured to up-convert the RF reference signal,

Wherein the processing circuitry is configured to generate the multi-channel image by mixing the second RF signal with the upconverted RF reference signal.

144. The apparatus of claim 143, wherein the up-conversion circuitry is configured to up-convert the RF reference signal by a factor between 30 and 80.

145. The apparatus of any one of claims 143-144, wherein the signal generator is configured to generate the RF reference signal to be chirped (chirped).

146. The apparatus of any of claims 138-145, wherein the frequency band further comprises a third sub-band, wherein the multi-channel image further comprises a third channel, and wherein the processing circuitry is further configured to determine data in the third channel using frequency components of the second RF signal in the third sub-band.