CN109782361B

CN109782361B - High-gain receiver applied to millimeter wave passive imaging

Info

Publication number: CN109782361B
Application number: CN201910022283.2A
Authority: CN
Inventors: 马顺利; 任俊彦; 魏继鹏; 李宁; 叶凡
Original assignee: Fudan University
Current assignee: Fudan University
Priority date: 2019-01-10
Filing date: 2019-01-10
Publication date: 2020-12-22
Anticipated expiration: 2039-01-10
Also published as: CN109782361A

Abstract

The invention belongs to the technical field of integrated circuits, and particularly relates to a high-gain receiver applied to millimeter wave passive imaging. The invention adopts a super-regenerative receiver circuit, which comprises: the circuit comprises an input matching network, a transformer matching network and an envelope detector, wherein the transformer matching network comprises a differential transistor pair. The invention can be used in passive imaging systems. Compared with the traditional passive millimeter wave imaging system, the high-gain receiver provided by the invention can realize ultra-wideband electromagnetic wave energy acquisition and 100dB gain, and can realize dynamic adjustment of the receiving range of the receiver by dynamically adjusting the bias voltage of the envelope detector. The invention adopts the gallium arsenide 0.15um process to realize the passive imaging from 80GHz to 100 GHz. The noise coefficient of the receiver is only 1.5dB, the gain of the receiver is 100dB, the dynamic range is 60dB, and the invention thoroughly overcomes the problem of bandwidth change caused by process error and temperature drift.

Description

High-gain receiver applied to millimeter wave passive imaging

Technical Field

The invention belongs to the technical field of integrated circuits, and particularly relates to a high-gain receiver used in a passive imaging circuit.

Background

The electromagnetic wave with the microwave frequency within the range of 30-300GHz, namely the wavelength within the range of 1-10mm is defined as millimeter wave, and the wavelength range is located between the microwave and the infrared wave, so that the electromagnetic wave has certain common characteristics with the microwave and the infrared wave and also has a plurality of unique characteristics. Compared with microwaves, under the condition that the diameters of the antennas are the same, the millimeter waves have the advantages of narrow wave beams, good directivity, excellent anti-interference performance, high resolution and good penetration characteristic in plasma; compared with infrared waves, the millimeter wave has better penetrating power and extremely strong diffraction performance, and the attenuation degree of substances such as gas, smoke, fog and the like under an atmospheric window is extremely small, so that the millimeter wave passive imaging technology has greater advantages than the traditional photoelectric imaging technology under severe meteorological conditions or under heavy smoke conditions such as military application and the like. The passive millimeter wave imaging system has an all-day uninterrupted working mode, has extremely high resolution, and can effectively identify target objects in the surrounding environment. Therefore, the millimeter wave passive imaging technology has important practical value in the fields of remote sensing, navigation, security inspection and the like.

The receiver front-end system is one of key components of the whole millimeter wave passive imaging system. Good rf front-end performance is very important for subsequent processing of the received signal. The technical index of the receiver can represent the most main technical level of a millimeter wave imaging system, and the receiver has the functions of signal amplification, linear conversion, calibration and the like. The sensitivity, linearity, stability of the receiver can characterize the imaging system's corresponding index. The sensitivity of the receiver characterizes the lowest input signal strength at which the receiver can function properly. The sensitivity is related to the system noise figure, bandwidth and signal modulation scheme. Different bandwidths can affect the noise power entering the system and thus the sensitivity of the receiver; different modulation modes have different requirements on the lowest detectable signal-to-noise ratio on the premise of ensuring that the bit error rate meets the requirements, and the sensitivity of the receiver is influenced. The lower limit of the dynamic range of the receiver is determined by the noise floor of the receiver system, and the upper limit is determined by non-linear indexes such as spurious-free dynamic range, third-order truncation point and the like. For the receiver system, the useful signal of the whole frequency band must be received to ensure that the signal is not distorted, i.e. the passband of the receiver system. A too narrow pass band may result in a useful broadband signal not passing through all, causing signal distortion; since the noise power is proportional to the bandwidth, too wide a pass band will result in too much noise power entering the system, and also in a reduction of the signal-to-noise ratio. Therefore, the development of the ultra-wideband high-gain receiver has important significance for the technical development of millimeter wave imaging.

Disclosure of Invention

In view of the above, the present invention is directed to a high-gain receiver applied to millimeter wave passive imaging.

The circuit structure of the high-gain receiver applied to millimeter wave passive imaging provided by the invention is shown in figure 1, and the high-gain receiver comprises the following modules: an input matching network 101, an ultra-wideband transformer matching network 102, an envelope detector 104; there is a differential NMOS transistor pair 103 in the ultra-wideband transformer matching network 102, where:

the input matching network 101 comprises four on-chip passive inductors, a middle tap of a right-end output inductor and a bias voltage V_BThe two differential NMOS transistor pairs are connected, and the upper end and the lower end of the two differential NMOS transistor pairs are respectively connected with the grid electrodes of the ultra-wideband transformer matching network 102;

a four-stage transformer is arranged in the ultra-wideband transformer matching network 102; each stage of transformer consists of a differential NMOS transistor pair and four on-chip passive inductors; the output ends (namely drain electrodes) of the two differential NMOS transistor pairs are connected with the upper end and the lower end of the two output inductors, the source electrodes of the differential NMOS transistor pairs are grounded, and the grid electrodes of the differential NMOS transistor pairs are respectively connected with the upper end and the lower end of the two input inductors; the middle taps of the two output inductors are connected with a power supply voltage VDD; the two output inductors pass through a bias voltage V_BIs coupled to the input of the next stage differential NMOS transistor pair; the signal is coupled to the input of the envelope detector 104 via a four-stage transformer;

the envelope detector 104 comprises two output differential NMOS transistor pairs M3, two input resistors R_BAn output resistor R_DAnd two blocking capacitors C_A(ii) a Two input inductors are connected with two DC blocking capacitors C_AOne end of (1), two DC blocking capacitors C_ARespectively connected to the gates of the output differential NMOS transistor pair M3, while a bias voltage V is applied_BThrough two input resistors R_BProviding a bias voltage to the output differential NMOS transistor pair M3; the drains of the output differential NMOS transistor pair M3 are connected to the power supply voltage VDD, the common source of the two output differential NMOS transistor pairs M3 is the output terminal, and the source thereof is connected to the output resistor R_DIs connected to an output resistor R_DAnd the other end of the same is grounded.

In the present invention, the receiving range of its receiver can be dynamically adjusted by adjusting the bias voltage of the envelope detector 104.

Preferably, in the present invention, the blocking capacitor C_AIs composed of an on-chip metal-insulator-metal capacitor (MIM-cap).

Preferably, in the present invention, the differential NMOS transistor pair is both MOSFETs, i.e., field effect transistors.

The invention can be used for a passive imaging system and images an object by detecting electromagnetic waves radiated by the object. Compared with the traditional passive millimeter wave imaging system, the high-gain receiver provided by the invention can realize ultra-wideband electromagnetic wave energy acquisition and 100dB gain, and can realize dynamic adjustment of the receiving range of the receiver by dynamically adjusting the bias voltage of the envelope detector. The invention adopts the gallium arsenide 0.15um process to realize the passive imaging from 80GHz to 100 GHz. The noise coefficient of the receiver is only 1.5dB, the gain of the receiver is 100dB, the dynamic range is 60dB, and the invention thoroughly overcomes the problem of bandwidth change caused by process error and temperature drift.

Drawings

Fig. 1 is a schematic diagram of a millimeter wave ultra-wideband passive imaging chip.

Fig. 2 is a schematic diagram of an ultra-wideband transformer.

Fig. 3 is an equivalent circuit diagram illustration of an ultra-wideband transformer.

Fig. 4 is a schematic diagram of a theoretical model of an ultra-wideband transformer.

Detailed Description

The high-gain receiver applied to millimeter wave passive imaging is further described with reference to the accompanying drawings. Like elements in the various figures are denoted by like reference numerals. For purposes of clarity, the various features in the drawings are not necessarily drawn to scale. Moreover, some well-known elements may not be shown in the figures.

Numerous specific details of the invention are set forth in the following description in order to provide a more thorough understanding of the invention. However, as will be understood by those skilled in the art, the present invention may be practiced without these specific details.

Fig. 1 shows a schematic diagram of a millimeter wave ultra-wideband passive imaging chip according to the prior art.

As shown in fig. 1, a conventional mm-wave ultra-wideband passive imaging chip 100 includes an input matching network 101, an ultra-wideband transformer matching network 102, and an envelope detector 104, an ultra-widebandThe strip transformer matching network includes a differential NMOS transistor pair 103. The input matching network 101 comprises four on-chip passive inductors, a middle tap of a right-end output inductor and a bias voltage V_BAnd the upper end and the lower end of the ultra-wideband transformer matching network are respectively connected with the grids of the two input NMOS transistors of the ultra-wideband transformer matching network. The ultra-wideband transformer matching network 102 is composed of two differential NMOS transistors and four on-chip passive inductors. The output of the two input NMOS transistors, namely the drain electrodes, are connected with the input ends of the two inductors at the left end, the source electrodes of the NMOS transistors are grounded, and the grid electrodes of the NMOS transistor pairs are respectively connected with the upper end and the lower end of the two input inductors; the middle tap of the right-hand inductor is connected with the power supply voltage VDD. The two output inductors are biased at a voltage V_BIs coupled to the input or gate of the next stage differential transistor. The signal is coupled to the input of the envelope detector via a four-stage ultra-wideband transformer. The envelope detector 104 comprises two NMOS transistors M3 (differential transistor pair), two input resistors R_BAn output resistor R_DAnd two blocking capacitors C_A. Two ends of the input are connected with two blocking capacitors C_A. Two blocking capacitors C_AThe other ends of the NMOS differential transistor pairs are respectively connected with the grid electrodes of the NMOS differential transistor pair M3, and simultaneously, the bias voltage V_BThrough two input resistors R_BA bias voltage is provided to the NMOS differential transistor pair M3. M3 has its drain connected to power supply voltage VDD, and two NMOS transistors with common source as output terminal for outputting a voltage signal and source connected to resistor R_DConnected by a resistor R_DAnd the other end of the same is grounded.

Fig. 2 shows a schematic diagram of an ultra-wideband transformer.

As shown in fig. 2, the transformer 200 is composed of three turns of an OI layer and two switches Switch. Wherein, two ends of the innermost coil are connected with the Switch2 through an EA layer; two ends of the middle coil are connected with ports P1 and P2 through an EA layer, and a middle tap of the middle coil is connected with a power supply voltage VDD; both ends of the outermost coil are connected to the Switch 1. The thickness of three rings OI layer is 3.3um, and the internal diameter of inlayer coil is 12um, and the internal diameter of middle coil is 22um, and the internal diameter of outermost coil is 32 um. The thickness of the EA layer is 0.9um. By changing the state of the switches Switch1 and Switch2, the equivalent inductance L of the transformer looking into the ports P1 and P2 can be changed_eq. State 1 of the switch represents closed and state 0 represents open. When the state of Switch (1, 2) is 00, the equivalent inductance L_eqA value of 91 pH; when the state of Switch (1, 2) is 10, the equivalent inductance L_eqHas a value of 79 pH; when the state of Switch (1, 2) is 01, the equivalent inductance L_eqA value of 65 pH; when the state of Switch (1, 2) is 11, the equivalent inductance L_eqThe value of (A) was 47 pH.

Fig. 3 shows an equivalent circuit diagram representation of an ultra-wideband transformer.

As shown in fig. 3, the equivalent circuit diagram of an ultra-wideband transformer includes an inductor, a capacitor, a variable capacitor, a resistor, and a transformer. Two inductors L_sConnecting two capacitors C_sThe two ends of the resistor are respectively connected with two capacitors C_sThe right pole plate is connected. A value of C_pCapacitance and variable capacitance C of/2_varConnected in parallel across the resistor. Variable capacitance C_varFor fine tuning, increasing inductance L_sCan increase the fine tuning range of the variable capacitance. The load inductance transformer at the back end is used for selecting the passband. The two switches connected across the inductor correspond to the switches Switch1 and Switch2 in fig. 2, respectively.

Fig. 4 shows a theoretical model diagram of an ultra-wideband transformer.

As shown in FIG. 4, the NMOS transistor is used as a switch, the gate of the NMOS transistor is connected to a control signal, the source is grounded, and the drain is connected to an inductor L₂The upper end of (a). When the control signal is 0, the NMOS switch is switched off; when the control signal is 1, the NMOS switch is closed. Equivalent inductance L_eqSlave inductor L₁The left end of the inductor L is seen into₁Is grounded, and an inductor L₂Is grounded, and an inductor L₁And L₂The ratio of turns of (a) is k. When the switch is turned on, the NMOS transistor is equivalent to a resistor R_on. At the moment, the theoretical model of the ultra-wideband transformer comprises three resistors and three inductors, wherein the resistor R₁Is connected with an inductor L₁Left end of M, inductance L₁-M and inductance L₂The common terminal of M is connected to one end of an inductor M, the lower end of the inductor M is connected to ground, and an inductor L₂The right end of M is connected with R₂Resistance R₂The other end of the resistor is connected with an equivalent resistor R of a conducting NMOS transistor_on. When the switch is turned off, the NMOS transistor is equivalent to a capacitor Coff. At the moment, the theoretical model of the ultra-wideband transformer comprises two resistors, three inductors and a capacitor, wherein the resistor R₁Is connected with an inductor L₁Left end of M, inductance L₁-M and inductance L₂The common terminal of M is connected to one end of an inductor M, the lower end of the inductor M is connected to ground, and an inductor L₂The right end of M is connected with a resistor R₂Resistance R₂The other end of the first and second transistors is connected with an equivalent capacitor C of a turn-off NMOS transistor_off。

In this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a list of elements (e.g., processes, methods, articles, or apparatus) that is included includes not only those elements but also other elements not expressly listed. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in addition to the element.

In the present invention, the embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Many variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A high-gain receiver applied to millimeter wave passive imaging is characterized in that a circuit structure comprises the following modules: an input matching network 101, an ultra-wideband transformer matching network 102, an envelope detector 104, the ultra-wideband transformer matching network 102 having a differential NMOS transistor pair 103, wherein:

the above-mentionedAn input matching network 101 including four on-chip passive inductors, a center tap of a right-end output inductor, and a bias voltage V_BThe two differential NMOS transistor pairs are connected, and the upper end and the lower end of the two differential NMOS transistor pairs are respectively connected with the grid electrodes of the ultra-wideband transformer matching network 102;

a four-stage transformer is arranged in the ultra-wideband transformer matching network 102; each stage of transformer consists of a differential NMOS transistor pair and four on-chip passive inductors; the four on-chip passive inductors are respectively provided with two output inductors and two input inductors; the output ends (namely drain electrodes) of the two differential NMOS transistor pairs are connected with the upper end and the lower end of the two output inductors, the source electrodes of the differential NMOS transistor pairs are grounded, and the grid electrodes of the differential NMOS transistor pairs are respectively connected with the upper end and the lower end of the two input inductors; the middle taps of the two output inductors are connected with a power supply voltage VDD; the two output inductors pass through a bias voltage V_BIs coupled to the input of the next stage differential NMOS transistor pair; the signal is coupled to the input of the envelope detector 104 via a four-stage transformer;

2. The high-gain receiver applied to millimeter wave passive imaging according to claim 1, wherein the blocking capacitor C is_AIs composed of an on-chip metal-insulator-metal capacitor.

3. The high-gain receiver applied to millimeter wave passive imaging according to claim 1, wherein the differential NMOS transistor pair is a MOSFET (field effect transistor).

4. The high gain receiver applied to millimeter wave passive imaging according to claim 1, wherein the receiving range of the receiver is dynamically adjusted by adjusting a bias voltage of the envelope detector 104.