JP2009288002A - Radar module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spread spectral radar module that reduces noise and distortion in a transmission line for transmitting signals, while ensuring isolation between transmission and reception. <P>SOLUTION: The spread spectral radar module integrated on a dielectric substrate includes: a transmitting section 24 for transmitting a wideband signal generated using a pseudo-noise code as a detection radio wave; a receiving section 37 for receiving the reflected wave of the detection radio wave which has been reflected by an object and returned and detecting the object from the received reflected wave using the pseudo-noise code; a signal source 21 for generating a narrowband signal; a transmission line 41a for transmitting the narrowband signal from the signal source 21 to the transmitting section 24; and a transmission line 42a for transmitting the narrowband signal from the signal source 21 to the receiving section 37. At least either one of the transmission line 41a and the transmission line 42a includes a filter section for cutting off a signal having the frequency of the detection radio wave. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a UWB (Ultra Wide Band) radar module using a spread spectrum system, and more particularly to a structure of a ground conductor that is electromagnetically coupled to a transmission line that requires high-speed transmission of a narrowband signal.

  In recent years, UWB radar devices are mounted on automobiles, and are used to detect preceding vehicles and rear obstacles. As a result, significant results are expected, such as improved safety such as collision avoidance and improved driving convenience represented by backward departure assistance.

  Along with this, various technologies relating to radar devices mounted on automobiles (hereinafter referred to as in-vehicle radar devices) have been proposed. As an example, a UWB radar device using a spread spectrum system (hereinafter referred to as a spread spectrum radar device) has been proposed (see, for example, Patent Document 1).

  For example, in an in-vehicle radar device, it is very important to suppress the influence of radio waves transmitted from the same type of radar device mounted on another vehicle. On the other hand, the radio wave transmitted from the spread spectrum radar apparatus is suppressed in the receiver in a radar apparatus using a different code sequence or another type of radar apparatus. Thus, the spread spectrum radar apparatus has little influence on other radar apparatuses. Even when radio waves are transmitted from other radar devices or wireless communication devices that use the same frequency band, the spread spectrum radar device has a large obstacle to the object detection capability. do not become.

  This is because the spread spectrum radar apparatus transmits radio waves that have been spread over a wide band using a pseudo-noise code (hereinafter referred to as a PN code). In addition, since the radio wave is frequency spread over a wide band, the power per unit frequency can be reduced, and the influence on other radar devices can be reduced. Furthermore, by adjusting the chip rate and code period of the PN code, the relationship between the distance resolution and the maximum detection distance can be set freely, and radio waves can be transmitted continuously, so that the peak power is It doesn't happen that it gets bigger.

  FIG. 12 is a block diagram illustrating an example of a functional configuration of a conventional general spread spectrum radar apparatus 10. The operation of the main part of the spread spectrum radar apparatus 10 shown in FIG. 12 will be described.

  The signal source 21 generates a narrowband signal that is not spread spectrum, and supplies the generated narrowband signal to the transmission unit 24 and the reception unit 37 through the transmission line 41 and the transmission line 42, respectively.

  The signal source 21 generates a narrowband signal having a frequency lower than the frequency actually used by the transmission unit 24 and the reception unit 37, and the multiplier 22 and the multiplier 31 are supplied to the transmission unit 24 and the reception unit 37, respectively. The arrived narrowband signal is converted into a frequency to be actually used by multiplying, for example, by 3.

  In the transmission unit 24, the spread modulation unit 23 spread-modulates the multiplied narrowband signal into a wideband signal using the PN code generated by the PN code generation unit 12.

  The transmission antenna 26 transmits a wideband signal input through the bandpass filter 25 as a detection radio wave.

  The reception antenna 39 receives the reflected wave of the detection radio wave returned from the object reflected by the object, and the low noise amplifier 38 amplifies the received signal.

  In the reception unit 37, the despreading modulation unit 33 uses the PN code delayed by the code delay unit 13 to despread-modulate the amplified received signal. By the orthogonal demodulation, the same frequency component as that of the narrowband signal included in the despread modulated reception signal is extracted.

The signal processing unit 57 detects the time delayed by the code delay unit 13 when the signal output from the despreading modulation unit 33 includes the same frequency component as the narrowband signal generated by the signal source 21. It is determined as the round-trip propagation time for radio waves. Further, a distance corresponding to the determined round-trip propagation time is determined as the distance to the object.
JP 7-12930 A

  By the way, the spread spectrum radar apparatus generally has a problem that the radar characteristics are deteriorated when the isolation between transmission and reception is insufficient. In the spread spectrum radar apparatus of FIG. 12, one of the causes of insufficient isolation is, for example, crosstalk between the transmission unit 24 and the reception unit 37 that occurs via the transmission line 41 and the transmission line 42.

  Therefore, when the spread spectrum radar apparatus is modularized, it is desirable that the transmission unit 24 and the reception unit 37 be installed as far apart as possible within a limited size called a module.

  However, when the transmission unit 24 and the reception unit 37 are separated from each other, the intervals between the signal source 21, the transmission unit 24, and the reception unit 37 are inevitably separated, and the transmission line 41 and the transmission line 42 are also long. End up.

  In the modular spread spectrum radar apparatus, the transmission line 41 and the transmission line 42 are formed on a dielectric substrate. Therefore, the longer the line is, the greater the electromagnetic coupling with the ground conductor. And is susceptible to strain.

  Therefore, the present invention has been made in view of the above problems, and provides a spread spectrum radar module that can suppress noise and distortion of a transmission line that transmits a signal while taking isolation between transmission and reception. With the goal.

  In order to achieve the above object, a spread spectrum radar module of the present invention is a spread spectrum radar module integrated on a dielectric substrate, and detects a wideband signal generated using a pseudo-noise code as a detection radio wave. A transmitting unit that transmits the received signal as a reflected wave of the detection radio wave reflected and returned by the object, and a receiving unit that detects the object from the received reflected wave using the pseudo-noise code; A signal source that generates a narrowband signal; a first transmission line that transmits the narrowband signal from the signal source to the transmitter; and a second that transmits the narrowband signal from the signal source to the receiver. A transmission line, and at least one of the first transmission line and the second transmission line has a filter unit that blocks a signal having the frequency of the detection radio wave.

  Here, at least one of the first transmission line and the second transmission line has a structure as the filter unit whose characteristic impedance is periodically different along the transmission direction of the narrowband signal.

  In the spread spectrum radar module, a plurality of ground conductors electromagnetically coupled to at least one of the first transmission line and the second transmission line are periodically arranged along a transmission direction of the narrowband signal. The width of at least one of the first transmission line and the second transmission line may be periodically different, and the first transmission line and the second transmission line may be different from each other. The at least one of the second transmission lines may be a coupled line composed of two lines, and the interval between the two lines may be periodically different.

  According to the spread spectrum radar module of the present invention, since the characteristic impedance of at least one of the first transmission line and the second transmission line is periodically different, it is preferable to select a repetition period in a section having different characteristic impedances. Thus, at least one of the first transmission line and the second transmission line can function as a notch filter that cuts off a signal for which crosstalk is to be reduced.

  Thereby, even if the lengths of the first transmission line and the second transmission line are made shorter than before, it is possible to obtain necessary isolation between the transmission unit and the reception unit. As a result, it is possible to provide an ideal spread spectrum radar module in which the influence of noise and distortion on the first transmission line and the second transmission line is suppressed and the signal is free from noise and distortion.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

  The spread spectrum radar apparatus according to the present embodiment is integrated as a spread spectrum radar module (hereinafter simply referred to as a module) on a dielectric substrate, and a radio wave for detection transmitted and received from an antenna is transmitted to a signal line for transmitting a narrowband signal. A filter unit that cuts off a signal having a frequency is provided.

  FIG. 1 is a block diagram showing the concept of the functional configuration of the spread spectrum radar apparatus 10a in the present embodiment. Compared to the conventional spread spectrum radar apparatus 10 of FIG. 12, the transmission line 41 and the transmission line 42 are changed to a transmission line 41a and a transmission line 42a, respectively. The transmission line 41a and the transmission line 42a have a filter unit that blocks a signal having a frequency of a detection radio wave transmitted and received from the antenna.

  As an example, this filter unit can be configured by periodically arranging portions having different characteristic impedances along the transmission line of the signal in the transmission line 41a and the transmission line 42a.

  FIG. 2 is a block diagram showing an example of a functional configuration of the spread spectrum radar apparatus 10b in the present embodiment. The transmission line 41b and the transmission line 42b in the spread spectrum radar apparatus 10b have a structure in which the characteristic impedance is periodically different along the signal transmission direction as a filter part of the transmission line 41a and the transmission line 42a in FIG.

  FIG. 3 is a top perspective view schematically showing an example of the configuration of a module in which a general spread spectrum radar apparatus is integrated on a semiconductor substrate. The module 65 in FIG. 3 corresponds to, for example, the spread spectrum radar apparatus 10 in FIG.

  In FIG. 3, the transmission chip 61 is an MMIC (Monolithic Integrated Circuit) formed on a semiconductor substrate, and corresponds to the transmission unit 24 of the spread spectrum radar apparatus 10. The transmission chip 61 is assumed. The receiving chip 62, the signal source chip 63, and the low noise amplifier chip 64 are also MMICs, and correspond to the receiving unit 37, the signal source 21, and the low noise amplifier 38 of the spread spectrum radar apparatus 10, respectively.

  The signal source chip 63 is provided at a position between the transmission chip 61 and the reception chip 62, connects the signal source chip 63 and the transmission chip 61 with the transmission line 41, and connects the signal source chip 63 and the reception chip 62 with the transmission line. Connect at 42.

  The transmitting antenna 26 and the receiving antenna 39 are installed on the back side of both ends of the module 65. In order to reduce transmission / reception signal loss, the transmitting chip 61 is mounted near the transmitting antenna 26 and the receiving chip 62 is mounted near the receiving antenna 39. For this reason, the distance between the transmission chip 61 and the reception chip 62 is almost from end to end of the module 65.

  As already pointed out as a problem, when the conventional transmission line 41 and transmission line 42 are used, it is necessary to lengthen the transmission line 41 and transmission line 42 in order to reduce crosstalk between transmission and reception. As the transmission line 42 becomes longer, the electromagnetic coupling with the ground conductor (not shown) increases, and the ground conductor is more susceptible to noise and distortion.

  FIG. 4A is a top perspective view schematically showing an example of the configuration of a module 65b in which the spread spectrum radar apparatus 10b according to the present embodiment is integrated on a semiconductor substrate.

FIG. 4B is a cross-sectional view taken along the line AA ′ in FIG.
The module 65b is substantially the same in configuration as the module 65 (FIG. 3), but a ground conductor 66 that is electromagnetically coupled to one of the transmission line 41b and the transmission line 42b is provided below the transmission line 41b and the transmission line 42b, respectively. The difference is that they are provided periodically along the signal transmission direction.

  A gap portion of the ground conductor 66 is filled with a dielectric 67. Therefore, the characteristic impedances of the transmission line 41 b and the transmission line 42 b are different between the part corresponding to the ground conductor 66 and the part corresponding to the dielectric 67.

The length of the ground conductor 66 in one cycle is l _A and the length of the dielectric 67 is l _B. The width of the region where the ground conductor 66 and the dielectric 67 are periodically provided is, for example, three times the width of the transmission line 41b and the transmission line 42b.

  With this configuration, the transmission line 41b and the transmission line 42b can function as a notch filter that blocks a signal having a specific frequency.

  FIG. 5 is a diagram illustrating an example of cutoff characteristics of the transmission line 41b and the transmission line 42b as notch filters.

The center frequency f _s of the notch in the transmission line 41b and the transmission line 42b is that the installation periods l _A and l _B of the ground conductor 66 and the dielectric 67 are ¼ of the signal wavelength in the transmission line 41a and the transmission line 42a. Is the frequency.

The narrowband signal that has reached the transmission chip 61 and the reception chip 62 is converted into a narrowband signal of another frequency (for example, three times the frequency of the narrowband signal from the signal source chip 63) using a multiplier inside. Are used for exchanging signals between the transmitting antenna 26 and the receiving antenna 39. That is, if the frequency of the narrowband signal output from the signal source chip 63 is f ₀ , the frequency of the signal used inside the transmission chip 61 and the reception chip 62 is 3f ₀ .

For this reason, by setting the center frequency f _{s of the} notch to 3f ₀ , the internal narrowband signals of the transmission chip 61 and the reception chip 62 cannot be transmitted through the transmission line 41b and the transmission line 42b. Isolation of is very easy to take.

  With this configuration, even if the transmission line 41b and the transmission line 42b are made shorter than the conventional transmission line 41 and the transmission line 42, the crosstalk generated between the transmission chip 61 and the reception chip 62 is suppressed to the same level as the conventional one. it can.

  By configuring the transmission line 41b and the transmission line 42b to be short, electromagnetic coupling between the transmission line 41b and the transmission line 42b and the ground conductor is reduced, and the influence of noise and distortion received from the ground conductor is reduced. In addition, the transmitting chip 61 and the receiving chip 62 can be arranged closer than before, which is useful for downsizing of the apparatus.

  In order to reduce the number of chips on the conventional general module 65 (FIG. 3), a composite transmission chip 68 in which the transmission chip 61 and the signal source chip 63 are combined may be used.

  FIG. 6 is a top perspective view schematically showing an example of the configuration of a general module 69 using such a composite transmission chip 68. Here, the composite transmission chip 68 corresponds to the transmission unit 24 and the signal source 21 of the spread spectrum radar apparatus 10.

  In the module 69, the signal from the signal source 21 is transmitted to the transmission unit 24 in the composite transmission chip 68, and is transmitted to the reception unit 37 through the transmission line 42.

  The present invention can also be applied to the transmission line 42 in the module 69.

  FIG. 7A is a top perspective view schematically showing an example of the configuration of a module 69b in a modification of the present embodiment.

FIG. 7B is a cross-sectional view taken along the line AA ′ in FIG.
The module 69b is similar to the module 65b (FIGS. 4A and 4B) in a rough configuration, but the transmission chip 61 and the signal source chip 63 are combined into one composite transmission chip 68. However, the transmission line 41b is omitted.

Since the configuration of the transmission line 42b and the effects obtained are the same as described above, description thereof is omitted.
In the module 69b, the transmission line 41b is omitted by integrating the signal source 21 and the transmission unit 24 in one composite transmission chip 68, but the signal source 21 and the reception unit 37 are integrated in one composite reception chip. Thus, a module in which the transmission line 42b is omitted can be considered.

  The transmitter chip 61, the receiver chip 62, and the signal source chip 63 may be those sealed in a package represented by a ceramic package. Further, the transmission line 41 and the transmission line 42 are not limited to one microstrip line, but may be a parallel two-line coupling line or a coplanar wave guideline.

(Second Embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings.

  As in the first embodiment, the spread spectrum radar apparatus according to the present embodiment is integrated as a module on a dielectric substrate, and the characteristic impedance of the signal line for transmitting the narrowband signal is determined by the transmission direction of the narrowband signal. It is characterized by being periodically different along

  FIG. 8A is a top perspective view schematically showing an example of the configuration of the module 65c in the present embodiment.

FIG. 8B is an enlarged view of the transmission line 41c and the transmission line 42c of FIG.
The module 65c is substantially the same in configuration as the module 65b (FIGS. 4A and 4B), but the periodic structure of the ground conductor 66 provided below the transmission line 41b and the transmission line 42b is omitted. Instead, the difference is that the widths of the transmission line 41c and the transmission line 42c are periodically different along the signal transmission direction.

The lengths of the thin portions of the transmission line 41c and the transmission line 42c in one cycle are l _A , and the length of the thick portion is l _B. Further, the ratio of the width of the narrow portion to the width of the thick portion is designed so that the impedance from end to end of the transmission line 41c and the transmission line 42c matches the characteristic impedance of the system.

  With this configuration, the transmission line 41c and the transmission line 42c can function as a notch filter that blocks a signal having a specific frequency.

Since the selection method of the length l _A and the length l _B is as described in the first embodiment, the description is omitted here.

  With this configuration, even if the transmission line 41c and the transmission line 42c are configured to be shorter than the conventional transmission line 41 and the transmission line 42, the crosstalk generated between the transmission chip 61 and the reception chip 62 is suppressed to the same extent as in the past. it can.

  By configuring the transmission line 41c and the transmission line 42c to be short, electromagnetic coupling between the transmission line 41c and the transmission line 42c and the ground conductor is reduced, and the influence of noise and distortion received from the ground conductor is reduced. In addition, the transmitting chip 61 and the receiving chip 62 can be arranged closer than before, which is useful for downsizing of the apparatus.

  The present invention can also be applied to the transmission line 42 in the module 69 (FIG. 6).

  FIG. 9 is a top perspective view schematically showing an example of the configuration of the module 69c in the modified example of the present embodiment.

  The module 69c is similar to the module 65c (FIGS. 8A and 8B) in a rough configuration, but the transmission chip 61 and the signal source chip 63 are combined into one composite transmission chip 68. However, the transmission line 41c is omitted.

Since the configuration of the transmission line 42c and the effects obtained are the same as described above, description thereof is omitted.
In the module 69c, the transmission line 41c is omitted by integrating the signal source 21 and the transmission unit 24 in one composite transmission chip 68, but the signal source 21 and the reception unit 37 are integrated in one composite reception chip. Thus, a module in which the transmission line 42c is omitted can be considered.

(Third embodiment)
Hereinafter, a third embodiment of the present invention will be described with reference to the drawings.

  As in the first embodiment, the spread spectrum radar apparatus according to the present embodiment is integrated as a module on a dielectric substrate, and the characteristic impedance of the signal line for transmitting the narrowband signal is determined by the transmission direction of the narrowband signal. It is characterized by being periodically different along

  FIG. 10A is a top perspective view schematically showing an example of the configuration of the module 65d in the present embodiment.

  FIG. 10B is an enlarged view of the transmission line 41d and the transmission line 42d in FIG.

  The module 65d is substantially the same as the module 65b (FIGS. 4A and 4B), but the periodic structure of the ground conductor 66 provided below the transmission line 41b and the transmission line 42b is omitted. Instead, the transmission line 41d and the transmission line 42d are coupled lines composed of two lines, and the difference is that the interval between the two lines constituting each coupled line is periodically different.

The length of the section where the distance between the two lines in each cycle is narrow is l _A , and the length of the section where the distance between the two lines is wide is l _B. The ratio between the narrow interval and the wide interval is designed so that the impedance from end to end of the transmission line 41d and the transmission line 42d matches the characteristic impedance of the system.

  With this configuration, the transmission line 41d and the transmission line 42d can function as a notch filter that cuts off a signal having a specific frequency.

Since the selection method of the length l _A and the length l _B is as described in the first embodiment, the description is omitted here.

  With this configuration, even when the transmission line 41d and the transmission line 42d are configured to be shorter than the conventional transmission line 41 and the transmission line 42, the crosstalk generated between the transmission chip 61 and the reception chip 62 is suppressed to the same level as in the past. it can.

  By configuring the transmission line 41d and the transmission line 42d to be short, electromagnetic coupling between the transmission line 41d and the transmission line 42d and the ground conductor is reduced, and the influence of noise and distortion received from the ground conductor is reduced. In addition, the transmitting chip 61 and the receiving chip 62 can be arranged closer than before, which is useful for downsizing of the apparatus.

  The present invention can also be applied to the transmission line 42 in the module 69 (FIG. 6).

  FIG. 11 is a top perspective view schematically showing an example of the configuration of the module 69c in a modification of the present embodiment.

  The module 69d is similar to the module 65d (FIGS. 10A and 10B) in a rough configuration, but the transmission chip 61 and the signal source chip 63 are combined into one composite transmission chip 68. However, the transmission line 41d is omitted.

  Since the configuration of the transmission line 42d and the effects obtained are the same as described above, the description thereof is omitted.

  In the module 69c, the transmission line 41d is omitted by integrating the signal source 21 and the transmission unit 24 in one composite transmission chip 68, but the signal source 21 and the reception unit 37 are integrated in one composite reception chip. Thus, a module in which the transmission line 42d is omitted can be considered.

  Although the spread spectrum radar module of the present invention has been described based on the embodiment, the present invention is not limited to this embodiment. Unless it deviates from the meaning of this invention, what made the various deformation | transformation which those skilled in the art conceivable to this Embodiment is also contained in the scope of the present invention.

  The present invention can be suitably used for a spread spectrum radar apparatus integrated as a module on a dielectric substrate.

The block diagram which shows the view of the functional structure of the spread spectrum radar apparatus concerning this invention 1 is a block diagram showing an example of a functional configuration of a spread spectrum radar apparatus according to the present invention. Top perspective view schematically showing an example of the configuration of a general spread spectrum radar module (A) Top perspective view schematically showing an example of the configuration of the spread spectrum radar module in the first embodiment, (B) The same sectional view The figure which shows an example of the cutoff characteristic as a notch filter of a transmission line Top perspective view schematically showing another example of the configuration of a general spread spectrum radar module (A) Top perspective view schematically showing an example of a configuration of a spread spectrum radar module in a modification of the first embodiment, (B) A sectional view of the same (A) Top perspective view schematically showing an example of the configuration of the spread spectrum radar module in the second embodiment, (B) Enlarged view of the transmission line The top perspective view which shows typically an example of a structure of the spread spectrum radar module in the modification of 2nd Embodiment (A) Top view perspective view schematically showing an example of the configuration of a spread spectrum radar module in the third embodiment, (B) Enlarged view of a transmission line The top perspective view which shows typically an example of a structure of the spread spectrum radar module in the modification of 3rd Embodiment Block diagram showing an example of a functional configuration of a conventional general spread spectrum radar apparatus

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 10a, 10b Spread-spectrum radar apparatus 12 PN code generation part 13 Code delay part 21 Signal source 22 Multiplier 23 Spreading modulation part 24 Transmission part 25 Band pass filter 26 Transmission antenna 31 Multiplier 33 Despreading modulation part 37 Reception part 38 Low noise amplifier 39 Reception antenna 41, 41a, 41b, 41c, 41d Transmission line 42, 42a, 42b, 42c, 42d Transmission line 57 Signal processor 61 Transmission chip 62 Reception chip 63 Signal source chip 64 Low noise amplifier chip 65, 65a , 65b, 65c, 65d Module 66 Ground conductor 67 Dielectric 68 Composite transmission chip 69, 69a, 69b, 69c, 69d Module

Claims (5)

A spread spectrum radar module integrated on a dielectric substrate,
A transmitter that transmits a broadband signal generated using a pseudo-noise code as a detection radio wave;
A receiving unit that receives a reflected wave of the detection radio wave reflected and returned from an object, and detects the object from the received reflected wave using the pseudo-noise code;
A signal source that generates a narrowband signal; and
A first transmission line for transmitting the narrowband signal from the signal source to the transmitter;
A second transmission line for transmitting the narrowband signal from the signal source to the receiving unit,
A spread spectrum radar module comprising: a filter section that cuts off a signal having the frequency of the detection radio wave in at least one of the first transmission line and the second transmission line. At least one of the first transmission line and the second transmission line has a structure as the filter unit whose characteristic impedance is periodically different along the transmission direction of the narrowband signal. Spread spectrum radar module. A plurality of ground conductors electromagnetically coupled to at least one of the first transmission line and the second transmission line are periodically provided along a transmission direction of the narrowband signal. The spread spectrum radar module according to claim 1. The spread spectrum radar module according to claim 1, wherein the width of at least one of the first transmission line and the second transmission line is periodically different. The at least one of the first transmission line and the second transmission line is a coupled line composed of two lines, and the interval between the two lines is periodically different. The spread spectrum radar module according to 1.

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