EP2707742A1

EP2707742A1 - Circuit configuration for radar applications

Info

Publication number: EP2707742A1
Application number: EP12711367.8A
Authority: EP
Inventors: Oliver Brueggemann; Christian Waldschmidt; Dirk Steinbuch; Thomas Binzer
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2011-05-10
Filing date: 2012-03-13
Publication date: 2014-03-19
Also published as: CN103502837A; US9726753B2; DE102011075552A1; US20150002330A1; WO2012152474A1

Abstract

The invention relates to a circuit configuration for radar applications, having a circuit board (12) and semiconductor modules (10) mounted thereon, each comprising an integrated circuit (16), a wiring layer (42) for connecting the integrated circuit (16) to the circuit board (12), and at least one antenna element (14) integrated in the semiconductor module (10) and connected to the integrated circuit (16) for transmitting and/or receiving radar signals, wherein the integrated circuit (16) comprises at least one HF oscillator (18) and a frequency splitter (26) connected thereto, wherein the circuit configuration comprises phase control circuits (24) for controlling the HF oscillators (18), wherein the phase control circuits (24) each comprise the frequency splitter (26) and a phase detector (28) for comparing a split-frequency signal of the HF oscillator (18) to a reference signal, and wherein the reference signals can be fed to the phase control circuits (24) by means of the circuit board (12).

Description

Title:

CIRCUIT ARRANGEMENT FOR RADAR APPLICATIONS

The invention relates to a circuit arrangement for radar applications, in particular motor vehicle radar applications. Furthermore, the invention relates to a radar sensor with such a circuit arrangement and a motor vehicle radar system with a circuit arrangement of this type.

STATE OF THE ART

Radar sensors are used for distance and / or speed measurement of objects. In particular, radar systems are known in which speeds and distances of several objects are detected simultaneously. For example, vehicle speed controllers for motor vehicles with a radar system for locating a vehicle ahead and for measuring the distance to it are known. Such a distance control system is also referred to as ACC (Adaptive Cruise Control) system.

Radar sensors are known that form distribution networks to antenna elements on HF substrates.

DE 10 2007 051 875 A1 describes an RF module with a printed circuit board device with a carrier, on which HF chips of HF chip modules are mounted. Several antenna devices may be centrally located on the front of each RF chip. On the two narrow sides of the front side of the RF chip are each in two rows of contact surfaces with which the RF chip is conductively connected to contacts of the substrate of the RF chip module. The assembly is done by flip chip technology. The substrates of the chip modules are in turn connected to connection areas with the printed circuit board device. To simplify the construction of RF circuits for radar applications, increasingly microwave integrated circuits of the MMIC type (Microwave Monolithic Integrated Circuit) are used for the transmission and reception circuits.

Wafer assemblies are known in which the assembly is fabricated with a rewiring layer for an IC device at the wafer level. Such a wafer assembly is also referred to as an embedded wafer level ball grid array (eWLB).

DE 10 2010 001 407 A1 describes a semiconductor module in which antennas are integrated at the wafer level. The semiconductor module comprises a first housing gold mass layer and an integrated circuit device with an integrated circuit that is embedded in the first housing gold mass layer. An intermediate layer comprises a redistribution layer which is connected to the IC device and serves to externally connect the IC device. An integrated antenna structure is disposed within the intermediate layer and is connected to the IC device. Such a semiconductor module can be assembled with suitable for the high frequency range of 77 GHz, for example, precision.

Such an eWLB semiconductor module with antennas integrated in the housing is also referred to as Antenna in Package (AiP).

DISCLOSURE OF THE INVENTION In an integrated circuit-integrated-antenna eWLB semiconductor module, for reasons of reliability and manufacturability, the spatial extent of the integrated circuit semiconductor module and antennas must not become arbitrarily large. Therefore, only one or a few antenna elements can be accommodated in the eWLB semiconductor module. Apertures of the antenna structures, which can not be realized within such a semiconductor module due to the limited size of an eWLB semiconductor module, are needed to construct long-range automotive radar sensors. The object of the invention is to provide a novel circuit arrangement for radar applications, which allows a structure of a radar sensor with a larger aperture.

This object is achieved according to the invention by a circuit arrangement for radar windings, with a printed circuit board and semiconductor modules mounted thereon, in which the semiconductor modules each have an integrated circuit, a rewiring layer for connecting the integrated circuit to the printed circuit board and at least one integrated in the semiconductor module, antenna element connected to the integrated circuit for transmitting and / or receiving radar signals, the integrated circuit comprising at least one RF oscillator and a frequency divider connected thereto, wherein the circuit arrangement comprises phase locked loops for controlling the RF oscillators, the phase locked loops respectively Frequency divider and a phase detector for comparing a frequency-divided signal of the RF oscillator having a reference signal, and wherein the phase locked loops via the circuit board, the reference signals can be fed.

By controlling the RF oscillators of the semiconductor modules by means of phase-locked loops whose frequency dividers are each formed in the integrated circuit of the semiconductor module, it is possible to couple the RF oscillators of the semiconductor modules via reference signals of lower frequency, in particular to synchronize, without requiring an HF Signal must be routed on the circuit board. The printed circuit board can thus be designed without an HF substrate. This simplifies the structure of the circuit considerably and is much cheaper to manufacture. In addition, the integration of the antenna elements into the semiconductor modules results in a particularly efficient and reliable construction. In particular, it is advantageous that a plurality of semiconductor modules can be coupled to eWLB packages with an integrated antenna, wherein all high-frequency-carrying components can be integrated in the respective semiconductor modules.

The RF oscillators are, in particular, oscillators for generating frequencies in the range of microwaves, that is to say decimetres, centimeters, and / or millimeter waves. For example, the phase-locked loops, and thus the RF oscillators, can be coupled via the reference signals that can be supplied to them via the printed circuit board. With several coupled RF oscillators with respective antenna elements, it is possible to realize apertures which exceed the extent of a semiconductor module. For example, coupled reference signals for the phase-locked loops can be provided, in particular reference signals based on a common reference signal. The common reference signal preferably has a frequency below 1 MHz, more preferably below 100 kHz.

Preferably, the phase locked loops can be coupled via a common reference signal which can be fed to them via the printed circuit board. The reference signals of the phase locked loops are thus each formed by the common reference signal.

Preferably, the semiconductor modules each comprise a wafer unit and an interface layer, wherein the wafer unit has a semiconductor chip forming the integrated circuit and a housing layer in which the semiconductor chip is embedded, and wherein the interface layer has the redistribution layer which connects the integrated circuit to the printed circuit board connects connected interfaces of the interface layer. In particular, the semiconductor module is preferably an eWLB package.

Preferably, the at least one antenna element is arranged in the interface layer. For example, the antenna element can be produced together with the redistribution layer in one method step. The at least one antenna element is arranged, for example, in the redistribution layer.

Preferably, the at least one antenna element is laterally offset from the semiconductor chip. By way of example, the at least one antenna element is arranged laterally offset relative to the semiconductor chip in an area outside the semiconductor chip in the interface layer. The wafer unit and the interface layer run, for example, in parallel, wherein the interface layer extends over a region of the semiconductor chip and over a region outside the semiconductor chip. In one embodiment, the circuit arrangement has an oscillator arranged on the printed circuit board for generating a reference signal, in particular a common reference signal. Preferably, the reference signal can be supplied to the phase locked loops via the printed circuit board. The oscillator is preferably a quartz oscillator. For example, the oscillator is an oscillator circuit comprising an oscillating quartz. As a result, a high constancy of the reference signal can be made possible.

In one embodiment, a plurality of the semiconductor modules are arranged in a regular arrangement in a row on the circuit board. Thus, a locally distributed positioning of the antenna elements integrated in the semiconductor modules can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are explained below with reference to the drawings.

Show it:

1 shows a schematic structure of a circuit arrangement of a radar sensor with monostatic antenna concept;

Fig. 2 is a schematic cross-sectional view of a semiconductor module of

Circuitry;

Figure 3 is a schematic representation of the structure of a radar sensor of a motor vehicle radar system with arranged in series antenna elements and a dielectric lens.

4 is a schematic representation of a matrix arrangement of antenna elements; and

Fig. 5 is a schematic view of an embodiment of a circuit arrangement with bistatic antenna concept. DESCRIPTION OF EMBODIMENTS

Fig. 1 shows schematically a circuit arrangement with a plurality of semiconductor modules 10, one of which is shown in cross-section in Fig. 2. The semiconductor modules 10 are mounted, for example, in a row on a printed circuit board 12. In Fig. 1, two of the semiconductor modules 10 are exemplified.

Each of the semiconductor modules 10 comprises an integrated antenna element 14 and an integrated circuit 16 in the form of a semiconductor chip. The antenna element is e.g. around a patch element, which serves in the example shown for transmitting and receiving a radar signal. The integrated circuit 16 comprises the RF part of a transmitting and receiving circuit and is connected to the antenna element 14.

In particular, the integrated circuit 16 includes an RF oscillator 18 for generating a radar signal for emission by the antenna element 14. Further, the integrated circuit 16 comprises, in a manner known per se, a mixer 20 for mixing the received radar signal with the transmitted signal. The antenna element 14 is connected, for example, via a coupler 21 in the form of a rat race ring with the oscillator 18 and the mixer 20 to separate the transmit and receive signals. The mixed RF signal is filtered, for example, and fed to an A / D converter 22 for further processing. The integrated circuit 16 is a so-called MMIC chip (Monolithic Microwave Integrated Circuit).

The frequency and phase of the controllable RF oscillator 18 is controlled by a phase-locked loop 24, which comprises a frequency divider 26, a phase discriminator or phase detector 28 and a loop or control filter 30. For example, the RF oscillator 18 is a voltage controlled oscillator (VCO, Voltage Contra II ed Oscillator). Via a conductor structure 32 on the printed circuit board 12, a common reference signal from an oscillator 34 is supplied to the phase detectors 28 of the respective phase locked loops. The oscillator 34 is a quartz oscillator comprising a quartz crystal. By the common reference signal the phase locked loops 24 are coupled together. In the example described, they are in particular synchronized so that the HF oscillators 18 oscillate synchronously. The respective phase detector 28 compares the signal of the HF oscillator divided by the frequency divider 26 with the reference signal supplied via the conductor structure 32. The control filter 30 converts the output signal of the phase detector 28 into a control signal for the controllable RF oscillator 18.

The integrated circuit 16 comprises, optionally with the exception of the rat race ring of the coupler 21, all the HF-leading components assigned to the respective antenna element 14. In particular, the integrated circuit 16 comprises not only the RF oscillator 18 but also the frequency divider 26 and the mixer 20. As described below, the respective antenna elements 14 and couplers 21 are integrated in the semiconductor modules 10. Thus, all the high frequency processing circuit parts of the circuit including the high frequency processing circuit parts of the phase locked loops may be integrated in the semiconductor modules 10. The printed circuit board 12 may therefore be a conventional printed circuit board without an RF substrate. This is made possible because only a low-frequency signal is required for coupling the phase-locked loops, and because, on the other hand, both the antenna elements and the HF-conducting circuit parts, including the frequency divider 26, are integrated in the respective semiconductor modules. FIG. 2 schematically shows the structure of one of the semiconductor modules 10.

The semiconductor module 10 is a so-called eWLB package in which a wafer unit comprises the semiconductor chip forming the integrated circuit 16 and a package gold mass layer which forms a package layer 38 in which the semiconductor chip is embedded. This wafer unit 36 assembled during production is also referred to as a reconstituted wafer. It is provided with an interface layer 40, which has a redistribution layer 42 and connections 44 in the form of 3D connection structures, in particular solder balls. The redistribution layer has pads on a first side that contact pads of the wafer unit 36. On a second side, the redistribution layer is connected to the terminals 44 for external contacting. That way is the integrated circuit 16 connected to the circuit board 12 connected to the terminals 44 of the interface layer 40. FIG. 2 shows by way of example four terminals 44, which are connected to strip conductors on the printed circuit board 12. The semiconductor module 10 can be applied to the printed circuit board 12 by standard processes, in particular surface-mount processes.

The antenna element 14 is also integrated in the interface layer 40 and connected to the integrated circuit 16 via the coupler 21, which is also integrated in the interface layer. In particular, the antenna element 14 and the coupler 21 are integrated into the interface layer as part of the redistribution layer 42. However, unlike the illustration in FIG. 1, the coupler 21 may also be integrated in the semiconductor chip of the integrated circuit 16, and the integrated circuit 16 may comprise the coupler 21.

The antenna element 14 is offset laterally with respect to the semiconductor chip and thus lies in the region next to the housing layer 38, outside a region of the interface layer 40 adjacent to the semiconductor chip. A main emission direction of the antenna element 14 perpendicular to the wafer unit 36 is shown in dashed lines in FIG. On the opposite side, the printed circuit board 12 is provided with a reflector 46 in the form of a conductive region. The antenna element 14 is connected via the coupler 21 via contact points on the first side of the redistribution layer 42 to the semiconductor chip. By integrating the antenna element 14 into the wafer-level semiconductor module with antenna in the housing (antenna in package, AiP), a precise connection of the antenna element is possible, so that a particularly efficient production is made possible. In particular, there is no need for an RF substrate on the printed circuit board compared to conventional antenna patches to be externally connected to an RF circuit. Nevertheless, the described coupled phase locked loops of the RF oscillators 18 can be used to achieve a defined phase relationship of the radar signals radiated by the antenna elements 14.

By means of this circuit arrangement, a radar front end of a radar sensor without an HF substrate can be realized, since only the low-frequency part of the phase-locked loop circle along with the other circuit elements on the circuit board 12 is located, while the high-frequency circuit parts are integrated in the semiconductor modules 10.

Fig. 3 shows schematically a radar sensor with an array of a series of antenna elements 14 of the circuit arrangement of Fig. 1. The antenna elements 14 are arranged in front of a beam shaping device 48 in the form of a dielectric cylindrical lens with a circular segment-shaped cross section. The antenna elements 14 are arranged side by side in the transverse direction (Y direction) and have a main radiation direction in the direction of the lens (X direction). The lens concentrates or focuses the radar signal in the vertical direction (Z-direction), i. concerning the elevation.

The beam shaping device may comprise further dielectric elements or lenses in a manner known per se, for example for the azimuthal focusing of the radar signal in the Y direction.

4 shows a variant in which the semiconductor modules, and thus the antenna elements 14, form a matrix arrangement on the printed circuit board 12. The antenna elements 14 are arranged at regular intervals in rows and columns in the Y direction and Z direction.

In the exemplary embodiments of FIGS. 3 and 4, the phase arrangement of the antenna elements 14 can be synchronized with one another by the circuit arrangement described above, so that conclusions are drawn about the direction of an object reflecting the radar signal in a manner known per se, for example from the phase position of the received signals can be.

While FIG. 1 shows a monostatic circuit arrangement in which the antenna elements 14 each act as a transmitting antenna and as a receiving antenna, FIG. 5 shows an example of a bistatic circuit arrangement in which separate semiconductor modules 50 with transmitting antenna elements 14 and semiconductor modules 60 with receiving antenna elements 14 In each case, the circuit arrangement corresponds to the circuit arrangement described with reference to FIG. 1, and the semiconductor modules 50, 60 are analogous to the circuit modules 10 built up. In this case, for example, the mixer 20 is provided only in the receiving semiconductor module 60. For example, a plurality of transmitting semiconductor modules 50 are arranged in a row, and a plurality of receiving semiconductor modules 60 are arranged in parallel therewith in a row. Once again, all high-frequency-carrying components are integrated together with the antenna elements 14 in the semiconductor modules 50, 60. In this case, the transmitting semiconductor modules 50 each comprise an antenna element 14 and an integrated circuit 56 in the form of a semiconductor chip, which comprises the RF oscillator 18 and the frequency divider 26. The receiving semiconductor modules 60 each comprise an antenna element 14 and an integrated circuit 66 in the form of a semiconductor chip, which comprises the RF oscillator 18, the frequency divider 26 and the mixer 20.

The radar sensor with one of the circuit arrangements described above is for example part of a motor vehicle radar system, in particular of a motor vehicle radar system for driver assistance.

In the examples described, a common reference signal is fed via the conductor structure 32 to the phase locked loop 24, which is used directly to drive the frequency divider 28 to synchronize the RF oscillators 18 with each other. Deviating from this, other forms of coupling of the RF oscillators are conceivable by reference signals supplied via the printed circuit board 12. Coupling, in particular a defined phase relationship between the RF oscillators 18 at the same or different oscillation frequencies, can be effected, for example, by supplying the common reference signal to the phase detector 28 via a frequency divider and / or a mixer. In this way, provided with a frequency offset reference signals can be supplied to the individual phase locked loops. The reference signals are based on the common reference signal. It is also conceivable to provide a plurality of coupled oscillators 34 for supplying the respective phase-locked loops via corresponding conductor structures 32.

In the examples described, the antenna elements are patch elements. But it can also antenna elements in the form of electric dipoles, for example printed dipoles, or magnetic dipoles.

Claims

- PATENT CLAIMS

A radar application circuit comprising a printed circuit board (12) and semiconductor modules (10) mounted thereon, the semiconductor modules (10) each having an integrated circuit (16), a redistribution layer (42) for connecting the integrated circuit (16) to the printed circuit board (12) and at least one in the semiconductor module (10) integrated, connected to the integrated circuit (16) antenna element (14) for transmitting and / or receiving radar signals, wherein the integrated circuit (16) at least one RF oscillator (18) and a frequency divider (26) connected thereto, the circuit arrangement comprising phase locked loops (24) for controlling the RF oscillators (18), the phase locked loops (24) respectively comprising the frequency divider (26) and a phase detector (28) for comparing a frequency-divided signal of the RF oscillator (18) having a reference signal, and wherein the phase locked loops (24) via the circuit board (12) the reference nzsignale can be fed.

2. A circuit arrangement according to claim 1, wherein the semiconductor modules (10) each have a wafer unit (36) and an interface layer (40), wherein the wafer unit (36) comprises a semiconductor chip which forms the integrated circuit (16) and a housing layer ( 38) in which the semiconductor chip is embedded, and wherein the interface layer (40) has the redistribution layer (42) connecting the integrated circuit (16) to terminals (44) of the interface layer (40) connected to the circuit board (12) ,

3. Circuit arrangement according to claim 2, wherein the at least one antenna element (14) in the interface layer (40) is arranged.

4. Circuit arrangement according to one of the preceding claims, wherein the circuit arrangement has an on the circuit board (12) arranged oscillator (34) for generating a reference signal.

5. Circuit arrangement according to claim 4, wherein the reference signal is a common reference signal for the phase locked loops.

6. Circuit arrangement according to one of the preceding claims, wherein a plurality of the semiconductor modules (10) in a regular arrangement in a row on the circuit board (12) are arranged.

7. Circuit arrangement according to one of the preceding claims, wherein a beam shaping device (48) is arranged in front of the semiconductor modules (10).

8. Circuit arrangement according to one of the preceding claims, wherein the semiconductor modules (10) form a matrix arrangement on the printed circuit board (12).

9. Radar sensor with a circuit arrangement according to one of claims 1 to 8.

10. Motor vehicle radar system with a circuit arrangement according to one of claims 1 to 8.