JP2008089614A - Radar sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor module that is optimized for miniaturization and cost reduction, in a radar sensor that utilizes millimeter-wave signalsof 20 GHz or higher or quasi-millimeter-wave signals. <P>SOLUTION: An oscillator comprising the radar sensor, an active circuit, such as mixer and antenna are formed integrally on the same semiconductor substrate, to constitute a single-chip MMIC 3. Furthermore, the MMIC 3 is encapsulated inside a resin package 1. A dielectric lens 2 is mounted on the upper side of the antenna to obtain a desired radiation angle. The lens and the resin package can be formed integrally by a metal mold, and cost reduction can be effected. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention detects a radar sensor, more specifically, a transmission signal, and detects the presence / absence of an object, a position, an object, or its own moving speed by receiving a reflection signal reflected by the object. The present invention relates to a receiver device (radar sensor) that receives transmission signal radiation and reflection signals of a radar device, and more particularly to a radar sensor that uses a millimeter wave or quasi-millimeter wave signal of 20 GHz or more as a transmission signal.

  2. Description of the Related Art Conventionally, radar devices (hereinafter, abbreviated as “radars”) that emit electromagnetic waves, receive a reflected wave reflected by a target, and detect the target have been widely used. In recent years, ultra-high frequency signals such as millimeter waves and quasi-millimeter waves have been used for the electromagnetic waves. A typical example of this type of radar using millimeter waves is an automobile radar used in an inter-vehicle distance warning system.

  Millimeter-wave modules used in these systems often have an active circuit such as an oscillator or a mixer mounted on a base plate and are hermetically sealed with a conductive package in order to shield external noise. . In addition, individual components such as diodes are also used for these active elements, but in recent years, MMICs (Monolithic Microwave Integrated Circuits) have been used for the purpose of reducing the size and weight of modules.

  However, when hermetically sealing with the above conductive package, the antenna needs to be arranged outside the conductive package, and there is a problem that the shape of the module becomes large. In addition, it is necessary to connect an active circuit inside the conductive package and an external antenna, which is not suitable for cost reduction of the module. In order to avoid such a problem, for example, in the technique disclosed in Patent Document 1, as shown in FIG. 5, the base plate 26 on which the active circuit 25 is mounted and the antenna 24 are connected to the same metal base plate. What is mounted on the same surface of 21 is known. In the example of FIG. 5, the planar antenna 24 is formed on the base plate 26. In addition, a radiation window 22 for radiating electromagnetic waves from the antenna 24 is provided above the antenna 24. The radiation window 22 is formed of a non-conductive material and is welded to the conductive package 23 for hermetic sealing. The radiation window 22 also functions as a dielectric lens for condensing the radiation angle of electromagnetic waves to a desired angle.

Japanese Patent Laid-Open No. 11-4118

  In in-vehicle radars and the like, it is extremely important to reduce the manufacturing cost as well as to reduce the size of the device. In the above-mentioned prior art, although suitable for miniaturization, a radiation window must be provided in the conductive package, and further, the radiation window and the conductive package must be welded for hermetic sealing. However, the package structure is still complicated and the manufacturing process is increased. Therefore, it is difficult to realize a millimeter wave radar sensor with a low manufacturing cost and cost.

  An object of the present invention is to realize a radar sensor operating at millimeter waves in a small size and at a low cost.

  In order to achieve the above object, the radar sensor according to the present invention comprises an active circuit such as an oscillator and a mixer coupled to an antenna and an antenna as an MMIC (monolithic microwave integrated circuit), and the MMIC and the antenna are packaged in a resin package. It is configured with sealing.

  In a preferred embodiment of the present invention, a lens is formed on a part of the resin package near the antenna. The lens may be made of the same material as that of the resin package and may be integrally formed, or the lens may be formed to be replaceable.

  The active circuit and the antenna can be configured by a plurality of MMIC chips and antennas, but a necessary active circuit may be realized by a single chip MMIC.

  Furthermore, the antenna may be configured on the same semiconductor substrate as the active circuit, and the antenna and the active circuit may be integrated into one chip.

  According to the present invention, the resin package can usually be molded by a mold, and the manufacturing cost can be significantly reduced. Further, since the resin package is non-conductive, a special structure such as a radiation window is provided above the antenna. Since it is not necessary to have a structure, this is also suitable for cost reduction.

  In particular, when realizing a radar sensor that radiates a high-frequency signal of 20 GHz or more and receives a reflected signal in which the high-frequency signal is reflected by an object, a dielectric lens is provided in a resin package so that a microstrip patch antenna or the like is provided. The area of the planar antenna can be reduced, the radar sensor can be downsized, and at the same time, the radiation angle of the antenna can be easily set. That is, in the case of a planar antenna such as a microstrip patch antenna, these antennas usually combine power with a plurality of antenna elements to obtain a desired radiation angle. Since the area of the IC is proportional to the cost, it is desirable that the number of antenna elements is small. Therefore, the radar sensor of the present invention has a configuration in which a desired radiation angle is obtained by providing a small number of antenna elements (ultimately one) and mounting a dielectric lens above the antenna.

  Further, when the dielectric lens and the resin package are separately prepared and bonded together, a plurality of shapes of dielectric lenses are manufactured, and the most suitable one is selected according to the application to be used. By adhering to, a radar sensor suitable for each application can be configured.

  It is desirable that the dielectric lens and the resin package have a relative dielectric constant of about 3 to 6 from the viewpoint of the size of the lens.

  According to the present invention, in a radar sensor that uses an ultra-high frequency signal such as a millimeter wave or a quasi-millimeter wave, the MMIC for the radar sensor is sealed with a resin package, and this is combined with a dielectric lens, thereby reducing the cost of the radar. Sensors can be manufactured.

  Furthermore, mass production is possible at low cost by integrally forming the dielectric lens with the resin package.

Embodiments of the present invention will be described below with reference to the drawings.
1 to 3 show a first embodiment of a radar sensor according to the present invention. FIG. 1 is a cross-sectional view of the radar sensor, FIG. 2 is an external plan view of the radar sensor, and FIG. 3 is a plan view when the upper portion of the package is removed. In this embodiment, the transmission IC 3 and the reception IC 4 are mounted in the same resin package 1. As shown in FIG. 3, the transmission IC 3 is a one-chip MMIC having an active circuit 7 for transmission and a transmission antenna 5 and formed on the same semiconductor substrate. Similarly, the reception IC 4 is a one-chip MMIC formed on the same semiconductor substrate with the reception active circuit 8 and the reception antenna 6. The transmitting IC 3 and the receiving IC 4 are fixed on the base plate 14. The connection between the transmitting IC 3 and the receiving IC 4 and the circuit outside the module is performed by connecting the wire 1 via the electrode pad of the MMIC and the connection pin 15 fixed to the outer periphery of the module.
6 is connected.

  In this embodiment, a dielectric lens 2 prepared separately from the resin package 1 is mounted on the resin package 1 above the planar antenna formed by the microstrip patch antenna constituting the transmitting antenna 5 and the receiving antenna 6. Both the transmitting antenna 5 and the receiving antenna 6 have one antenna element, and by collecting electromagnetic waves, the chip area is reduced, that is, the cost is reduced.

  FIG. 4 shows an equivalent circuit diagram of the chips 2 and 5 of the above embodiment, FIG. 4 (a) shows a circuit block diagram of the transmitting IC 3, and FIG. 4 (b) shows a circuit block diagram of the receiving IC 4. FIG. The transmitting IC 3 generates a high-frequency signal by the oscillator 9, amplifies it by the amplifier 10, and then radiates the signal from the transmitting antenna 5. This signal is reflected by the target, but this reflected signal is received by the receiving antenna 6 of the receiving IC 4, amplified by the low noise amplifier 13, and then the high frequency signal generated by the local signal generator 11 by the mixer 12. To generate an IF signal. In the ICs 3 and 4, if sufficient transmission power can be obtained without using the amplifier 10, the amplifier 10 may be omitted. Similarly, the low noise amplifier 13 can be omitted if sufficient reception sensitivity can be obtained without using the low noise amplifier 13.

  In this embodiment, the ICs 3 and 4 which are MMICs are sealed in the resin package 1. However, since the resin package 1 can be integrally formed with a mold, the mounting cost can be kept low. Furthermore, by using the same material for the dielectric lens and the resin package, the dielectric lens and the resin package can be integrally molded by a mold, and mass production can be achieved at low cost.

  Further, since the transmission antenna 5 is formed in the transmission IC 3 and the reception antenna 6 is formed in the reception IC 4, a high frequency signal does not flow through the bonding portion, so that no special mounting technique is required.

  In the present embodiment, the resin package 1 and the dielectric lens 2 can be reduced in cost by being integrally molded. However, when they are separately molded, depending on the application to be used, that is, the frequency of the high frequency, the shape of the antenna If multiple types of optimized lenses such as the shape of the radiation electromagnetic wave beam are prepared, it can be used for various types of applications depending on the application. Yes.

  FIG. 6 is a plan view of another embodiment of a radar sensor according to the present invention. In this embodiment, the transmitting IC and the receiving IC are realized by one chip. In this embodiment, the active circuit unit 33 including both the transmission circuit and the reception circuit, the transmission antenna 37 and the reception antenna 38 are formed on the same semiconductor substrate 31, and the transmission antenna 37 and the reception antenna are centered on the active circuit unit 33. The radar IC 31 is configured by monolithic arrangement so that the antenna 38 is a target.

  FIG. 7 shows an equivalent circuit diagram of a circuit formed by the radar IC 31 of the other embodiment. In the present embodiment, the same oscillator is used as the oscillator for generating the transmission signal and the local signal generator that is input to the mixer. The high-frequency signal generated by the oscillator 34 is distributed by the power distributor 17, and one is used as a transmission signal and the other is used as a local signal to be input to the mixer. The transmission signal is amplified by the amplifier 10 and then transmitted from the transmission antenna 37. The reflected signal is received by the receiving antenna 38, and an IF signal is generated by the mixer 12 via the low noise amplifier 13. Also in this embodiment, the amplifier 10 may be omitted when sufficient transmission power is obtained, and the low noise amplifier 13 may be omitted when sufficient reception sensitivity is obtained. According to the present embodiment, the IC for the radar sensor is composed of the one-chip MMIC 31, and the cost for mounting can be further reduced. In addition, a present Example can be simplified by using the antenna 39 which used both transmission and reception as shown in FIG.

  FIG. 9 is a circuit diagram showing a configuration of an embodiment of the MMIC 31 constituting the radar sensor according to the present invention. This circuit can be simplified by using the self-oscillation mixer 40 and the transmitting / receiving antenna 39 as in the equivalent circuit (a). As shown in FIG. 5B, an antenna 39 is connected to a single FET and the drain terminal of the FET via a distributed constant line 45-2. Further, a distributed constant line 45-1 and a power supply terminal Vd are connected to the drain terminal. The power supply terminal Vd also serves as an intermediate frequency output. Vg is connected to the gate terminal of the FET through a resistor 48. An impedance element 47 is also connected to the gate terminal. An open stub type resonator 45-3 is connected to the source terminal of the FET, and a varactor diode 46 for frequency adjustment is connected to the tip of the resonator. A control voltage terminal is connected to the varactor diode 46 via a resistor 49. Furthermore, the source terminal of the FET is grounded via the λ / 4 distributed constant line 45-4. In the figure, E represents grounding and is grounded to the MMIC substrate.

  FIG. 10 shows a side sectional view of still another embodiment of the radar sensor according to the present invention. In this embodiment, a sensor IC 31 and a signal processing IC 42 are mounted in a resin package 1. The signal processing IC 42 is, for example, an IC for processing an FFT (Fourier transform) signal on an IF signal generated by a radar sensor.

  According to the present embodiment, it is possible to realize a more advanced radar sensor by performing signal processing on the signal output from the radar sensor IC31.

  FIG. 11 shows a side sectional view of yet another embodiment of a radar sensor according to the present invention. In each of the above-described embodiments, the package is filled with the same resin. However, a part of the package may be formed using another resin. In the embodiment of FIG. 11, another resin 43 is used in a portion in contact with the MMIC 31. In particular, since the high frequency performance of the material in contact with the MMIC greatly affects the sensor performance, a higher performance sensor can be realized by using a material with low dielectric loss and good high frequency characteristics. Further, when it is desired to completely remove the influence of the resin, this portion may not be filled with the resin but may be in a state such as air, vacuum, or nitrogen filling.

  Furthermore, as shown in FIG. 12, when the same material is used for a portion of the resin 44 and the dielectric lens 2 in the package, the manufacturing cost can be reduced. By using another resin for a part of the package as in these embodiments, it is possible to make a higher performance sensor, especially in a part that is in contact with the MMIC or a part where a high frequency signal passes such as above the antenna. It is effective to use a material with good high frequency characteristics.

1 is a cross-sectional view of a first embodiment of a radar sensor according to the present invention. 1 is a schematic plan view of a first embodiment of a radar sensor according to the present invention. The top view except the upper part of the 1st Example of the radar sensor by this invention. The equivalent circuit schematic of IC in the 1st Example of this invention. Sectional drawing of an example of the conventional radar sensor. The top view of the 2nd Example of the radar sensor by this invention. The equivalent circuit schematic of the 2nd Example of the radar sensor by this invention. The equivalent circuit schematic of the 3rd Example of the radar sensor by this invention. The circuit diagram of the 4th example of the radar sensor by the present invention. FIG. 6 is a side sectional view of a fifth embodiment of a radar sensor according to the present invention. FIG. 10 is a side sectional view of a sixth embodiment of a radar sensor according to the present invention. FIG. 9 is a side sectional view of a seventh embodiment of a radar sensor according to the present invention.

Explanation of symbols

1: Resin package, 2: Dielectric lens, 3: Transmission IC, 4: Reception IC
5: transmitting antenna, 6: receiving antenna, 7: active circuit for transmission,
8: active circuit for reception, 9: oscillator for transmission, 10: amplifier,
11: Local signal generator, 12: Mixer, 13: Low noise amplifier,
14: base plate, 15: electrode pin, 16: wire, 17: power distributor,
19: Circulator, 21: Base plate, 22: Radiation window and dielectric lens, 23: Conductive package, 24: Antenna, 25: Active circuit,
26: base plate, 31: IC for radar sensor, 33: transmission / reception active circuit, 34: oscillator, 37: transmission antenna, 38: reception antenna,
39: antenna for transmitting and receiving, 40: self-oscillating mixer, 42: signal processing IC,
43: second resin, 44: second resin, 45: distributed constant line, 46: diode: 47: impedance element, 48, 49: resistance.

Claims (27)

An antenna,
An active circuit coupled to the antenna and configured with an MMIC;
A resin package that is filled with the same resin and that seals the antenna so that the resin contacts the active circuit;
Comprising a connection pin electrically connected to the MMIC via a wire,
The antenna and the active circuit are configured on a common semiconductor substrate to form a single chip,
A dielectric lens is formed on the resin package in the vicinity of the antenna,
A radar sensor, wherein the MMIC is electrically connected to the outside of the resin package via the connection pin. In claim 1,
A radar sensor, wherein the dielectric lens is integrally formed of the same material as the resin package. In claim 1,
2. The radar sensor according to claim 1, wherein the dielectric lens is formed by adhering a dielectric lens separately from the resin package onto the resin package. In any of claims 1 to 3,
A radar sensor characterized in that the dielectric lens material has a relative dielectric constant in the range of 3 to 6. In any of claims 1 to 4,
The active circuit includes an oscillator and a mixer. In claim 5,
A radar sensor, wherein a frequency of a transmission signal transmitted from the active circuit is 20 GHz to 100 GHz. In claim 5,
The active circuit further comprises a signal processing circuit for processing the output of the active circuit. A transmission circuit for transmitting a transmission signal;
A receiving circuit for receiving a reflected signal based on the transmitted signal;
A transmission antenna that radiates the transmission signal generated by the transmission circuit;
A receiving antenna that receives the reflected signal and supplies the reflected signal to the receiving circuit;
Resin that is filled with the same resin and that integrally seals the transmission circuit, the reception circuit, the transmission antenna, and the reception antenna so that the resin contacts the transmission circuit and the reception circuit Package and
Comprising a connection pin electrically connected to at least one of the transmission circuit and the reception circuit via a wire,
The transmission circuit, the reception circuit, the transmission antenna, and the reception antenna are formed on a single MMIC chip,
A dielectric lens is formed on the resin package so as to cover the transmitting antenna and the receiving antenna,
A radar sensor, wherein at least one of the transmission circuit and the reception circuit is electrically connected to the outside of the resin package via the connection pin. A transmission circuit for transmitting a transmission signal;
A receiving circuit for receiving a reflected signal based on the transmitted signal;
A transmission antenna that radiates the transmission signal generated by the transmission circuit and is electrically connected to the transmission circuit;
A receiving antenna electrically connected to the receiving circuit for receiving the reflected signal and supplying the reflected signal to the receiving circuit;
Resin that is filled with the same resin and that integrally seals the transmission circuit, the reception circuit, the transmission antenna, and the reception antenna so that the resin contacts the transmission circuit and the reception circuit Package and
Comprising a connection pin electrically connected to at least one of the transmission circuit and the reception circuit via a wire,
The transmission circuit and the transmission antenna are formed on a first MMIC chip,
The receiving circuit and the receiving antenna are formed on a second MMIC chip different from the first MMIC chip,
A dielectric lens is formed on the resin package so as to cover the transmitting antenna and the receiving antenna,
A radar sensor, wherein at least one of the transmission circuit and the reception circuit is electrically connected to the outside of the resin package via the connection pin. In claim 8,
A radar sensor, further comprising a signal processing circuit for processing an output from at least one of the transmission circuit and the reception circuit. In claim 10,
The radar sensor according to claim 1, wherein the signal processing circuit is formed on the MMIC. In claim 10,
2. The radar sensor according to claim 1, wherein the signal processing circuit is formed on a signal processing chip mounted in the resin package, which is different from the MMIC. In claim 9,
A signal processing circuit for processing an output from at least one of the transmission circuit and the reception circuit;
The radar sensor according to claim 1, wherein the signal processing circuit is formed on a signal processing chip mounted in the resin package, which is different from the first and second MMIC chips. In claim 8,
2. The radar sensor according to claim 1, wherein the dielectric lens is integrally formed of the same material as the resin package. In claim 8,
2. The radar sensor according to claim 1, wherein the dielectric lens is formed by adhering a dielectric lens separately from the resin package onto the resin package. In claim 15,
A radar sensor characterized in that the dielectric lens material has a relative dielectric constant in the range of 3 to 6. In claim 16,
2. The radar sensor according to claim 1, wherein the transmitting antenna and the receiving antenna are arranged so as to be substantially symmetrical about the transmitting circuit and the receiving circuit. In claim 16,
The radar sensor according to claim 1, wherein the frequency of the transmission signal is 20 GHz to 100 GHz. An active circuit unit including both a transmission circuit and a reception essential circuit;
A transmission antenna that radiates a transmission signal generated by the active circuit unit;
A receiving antenna that receives a reflected signal of the radiated transmission signal and supplies the reflected signal to the active circuit unit;
A resin package that is filled with the same resin and that integrally seals the active circuit portion, the transmitting antenna, and the receiving antenna so that the resin contacts the active circuit;
Comprising a connection pin electrically connected to the active circuit part through a wire,
The active circuit unit, the transmitting antenna, and the receiving antenna are integrally formed on a single MMIC chip,
A dielectric lens is formed on the resin package above the transmitting antenna and the receiving antenna,
A radar sensor, wherein the MMIC is electrically connected to the outside of the resin package via the connection pin. In claim 19,
A radar sensor, further comprising a signal processing circuit for processing an output from the active circuit unit. In claim 20,
The radar sensor according to claim 1, wherein the signal processing circuit is formed on the MMIC. In claim 20,
2. The radar sensor according to claim 1, wherein the signal processing circuit is formed on a signal processing chip mounted in the resin package, which is different from the MMIC. In claim 19,
2. The radar sensor according to claim 1, wherein the dielectric lens is integrally formed of the same material as the resin package. In claim 19,
2. The radar sensor according to claim 1, wherein the dielectric lens is formed by adhering a dielectric lens separately from the resin package onto the resin package. In claim 24,
A radar sensor characterized in that the dielectric lens material has a relative dielectric constant in the range of 3 to 6. In claim 25,
The radar antenna, wherein the transmitting antenna and the receiving antenna are arranged so as to be substantially symmetrical about the active circuit. In claim 25,
A radar sensor, wherein the frequency of the transmission signal operates at a frequency of 20 GHz to 100 GHz.

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