KR100751065B1 - RF transceiver module and millimeterwave FMCW radar sensor using the same - Google Patents

Abstract

The present invention relates to an RF transmit / receive module capable of improving reception sensitivity by improving a connection structure between key components, and a millimeter wave FMCW radar sensor using the RF transmit / receive module. The RF transceiver module according to the present invention includes a power divider for distributing a modulated signal generated by a voltage controlled oscillator, and multiplies and amplifies the modulated signal, and transmits the amplified modulated signal through a transmitting antenna from a power divider. A balanced mixer which up- and down-converts the modulated signal from the local oscillator using the local oscillator signal and outputs the converted first and second signals, and receives the signal received through the receiving antenna through the downlink frequency mixer. And a receiving end for mixing the first signal down-mixed and the down-mixed third signal with the second signal through an intermediate frequency mixer and outputting the mixed signal.

FMCW radar, millimeter wave, RF transmit / receive module, MMIC

Description

RF transceiver module and millimeterwave FMCW radar sensor using the same}

1 is a block diagram of a millimeter wave FMCW radar sensor employing an RF transceiver module according to an embodiment of the present invention.

2 is a block diagram of an RF transceiver module according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

10: RF transmission and reception module 11: antenna unit

12: RF transceiver 13: Modulator

14: Analog Circuit 15: A / D Converter

16: FFT (Fast Fourier Transform) section 17: Digital signal processing section (DSP)

18: display unit 19: CAN interface unit

20: ECU processor

101: Tx Antenna

102: Power Amplifier

103: Drive Amplifier

104: Frequency Doubler

105: power divider

106: Voltage Controlled Oscillator (VCO)

107: Balanced Mixer (Mixer)

108: Local Oscillator (LO)

109: Rx Antenna

110, 114: Amplifier

111: Low Noise Amplifier (LNA)

112: Down-Mixer

113: Band Pass Filter (BPF)

115: IF Mixer

116: IF Amplifier

117: transmitting end

118: signal source block

119: receiving end

120: intermediate frequency block

The present invention relates to an RF transmit / receive module capable of improving reception sensitivity by improving a connection structure between key components, and a millimeter wave FMCW radar sensor using the RF transmit / receive module.

In general, the vehicle radar sensor includes an ultrasonic radar, an image sensor, a laser sensor, and a millimeter wave radar, depending on the applied technology. Ultrasonic lasers can be implemented small and inexpensive, but the reception sensitivity is small. It is easy to be affected by the environment, and is not suitable for obstacle detection at high speeds. The image sensor has a disadvantage in that it is not easy to detect an obstacle in real time due to complicated image processing and the like, and the performance drops sharply in bad weather. The laser sensor was developed to detect long-distance obstacles using near-infrared laser, but its performance deteriorates rapidly in weather conditions such as fog and rain. On the other hand, millimeter wave radar is known to be most suitable for vehicle radar sensors because of its small performance difference in all-weather conditions such as bad weather and day and night.

A millimeter wave frequency modulated continuous wave (FMCW) radar sensor is typically composed of an RF transceiver module, a digital signal processing (DSP) unit for signal processing, a CAN interface unit, a display unit, and a processor. The RF transmit / receive module includes a voltage controlled oscillator (VCO) for generating an FMCW modulated signal, an amplifier for amplifying a millimeter wave output signal of the voltage controlled oscillator, a transmitting antenna for transmitting the amplified signal, and a signal reflected to a target. It consists of a receiving antenna for receiving, a low noise amplifier for amplifying the received signal, a mixer for detecting a bit signal containing information of relative speed and distance from the received signal, and an IF unit for processing the bit signal.

On the other hand, the RF transceiver module for millimeter wave radar sensor using MMIC (Monolithic Microwave Integrated Circuit) is located at the front end of the radar sensor and is a key component for wireless communication, and the reception sensitivity of the RF transceiver module is the reception of the radar sensor. This is a very important factor in determining distance. Therefore, in order to increase the reception distance of the RF transmission / reception module, the reception sensitivity of the RF transmission / reception module should be improved.

However, the reception sensitivity of the conventional RF transmission / reception module using the homodyne method has a problem that the transmission modulation signal affects the reception signal, resulting in poor separation characteristics of the receiver, thereby making it impossible to receive the high sensitivity of the radar sensor. There is this.

Accordingly, the present invention proposes a structure for improving reception sensitivity and separating transmission / reception signals from the existing homodyne scheme in configuring an RF transceiver module for a vehicle radar. Specifically, the RF transceiver module used in the millimeter wave FMCW radar sensor is composed of a transmitter consisting of a voltage controlled oscillator, a frequency multiplier, a driving amplifier, a power amplifier, a frequency distribution circuit, a low noise amplifier, a downlink mixer, a filter, and an intermediate frequency amplifier. In the present invention, a local oscillator L0 for generating an arbitrary signal fa and a mixer for equilibrium mixing of the signal fa with a modulation output signal fo + fm coming from the voltage controlled oscillator of the transmitting stage. A voltage controlled oscillator of a conventional transmitter stage by injecting the mixer and the first signal (fo + fm + fa) and the second signal (fo + fm-fa) from the mixer into two frequency mixers of the receiver stage, respectively. It eliminates signal interference between transmitters and receivers when direct modulation signal is used and improves signal reception sensitivity of RF transceiver module. The purpose is to provide a permissible RF transceiver module.

It is also an object of the present invention to provide a millimeter wave frequency modulated continuous wave (FMCW) radar apparatus using the above-described RF transceiver module.

According to a preferred aspect of the present invention for achieving the above object, it comprises a power divider for distributing the modulated signal (fo + fm) generated by the voltage controlled oscillator, multiplying and amplifying the modulated signal, the amplified A transmitter for radiating a modulated signal (2fo + 2fm) through a transmission antenna; The modulated signal from the power divider is up- and down-converted using the local oscillation signal fa from the local oscillator, and the converted first signal fo + fm + fa and the second signal fo + fm-fa Equilibrium mixing unit for outputting; And down-mixing the signal (2fo + fb + 2fm) received through the receiving antenna with the first signal through a downlink frequency mixer, and mixing the downlinked third signal (fo + fb-fa + fm) into the intermediate frequency mixer. There is provided an RF transceiver module for a radar sensor, comprising a receiving end for mixing with the second signal and outputting the mixed signal fb.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments described below are not intended to limit the scope of the invention, but are presented by way of example only.

1 is a block diagram of a millimeter wave FMCW radar sensor employing an RF transceiver module according to an embodiment of the present invention.

Referring to FIG. 1, the millimeter wave FMCW radar sensor according to the present embodiment is connected to an RF transmitting / receiving module 10 including an transmitting / receiving antenna unit 11 and an RF transmitting / receiving unit 12 and an output terminal of the RF transmitting / receiving module 10. Analog circuit 14, A / D converter 15 connected to the output terminal of the analog circuit 14, FFT (Fast Fourier Transform 16) connected to the output terminal of the A / D converter 15, FFT ( 16 is connected to the output terminal of the digital signal processor 17, a display unit (18) connected to the digital signal processor 17 and displays information received from the received signal, the digital signal processor 17 and the ECU (Electronic Control) A modulator connected to the CAN interface 19 coupled between the processor 20 and the input terminal of the RF transmission / reception module 10 and modulating an arbitrary signal in response to the control of the digital signal processor (DSP) 17. A modulator;

The operation of the millimeter wave FMCW radar sensor described above is as follows. First, the FMCW modulated signal through the modulator 13 is loaded on the millimeter wave by the RF transceiver 12 of the RF transceiver module 10 and then amplified and transmitted through the transceiver antenna 11. The transmitted signal is received through the transmit / receive antenna unit 11 as a received signal including the relative speed and distance data between the target and the radar system after returning to the target after being reflected, and RF transmit / receive of the RF transmit / receive module 10. The unit 12 converts the bit signal having the relative velocity and distance data and then transfers the analog signal to the analog circuit 14. Thereafter, the transmitted signal is digitally processed by the digital signal processing unit 17 through Fourier transform of the FFT 16 via the A / D converter 15. The digital signal processor 17 operates the modulator 13 for FMCW modulation, transmits information to the display 18 to display data on the screen, and transmits the data to the ECU processor 20 through the CAN interface 19. .

The RF transceiver module used in the above-described millimeter wave FMCW radar sensor exhibits excellent performance in terms of dynamic range characteristics and detectable distance of the entire sensor according to its structure. Therefore, the millimeter wave FMCW radar sensor of the present invention improves the characteristic that the detection range is not sufficiently secured by reducing the dynamic range of the sensor module due to the reception signal interference of the transmission signal, which is a disadvantage of the conventional homodyne vehicle FMCW radar structure. , Improved reception sensitivity in all weather conditions such as weather conditions and bad weather, day and night. Referring to the RF transmission and reception module according to the present invention in detail.

2 is a block diagram of an RF transceiver module according to an embodiment of the present invention.

Referring to FIG. 2, the RF transceiver module according to the present invention includes a transmission antenna 101, a power amplifier 102, a drive amplifier 103, a frequency multiplier 104, a power divider 105, and a voltage controlled oscillator 106. , Balanced frequency mixer 107, local oscillator 108, receive antenna 109, first amplifier 110, low noise amplifier 111, downlink frequency mixer 112, bandpass filter 113, second amplifier 114, an intermediate frequency mixer 115, and an intermediate frequency amplifier 116. The power amplifier 102, the drive amplifier 103 and the frequency multiplier 104 constitute a transmitting stage 117, the voltage controlled oscillator 106 and the power divider 105 constitute a signal source block 118, and local The oscillator 108 and the balanced frequency mixer 107 constitute a balanced mixer for up- and down-converting the modulated signal obtained from the transmitter 117 to the receiver 119, and the first and second amplifiers 110 and 114. The low noise amplifier 111, the downlink frequency mixer 112, the bandpass filter 113, the intermediate frequency mixer 115, and the intermediate frequency amplifier 116 constitute a receiving end 119.

In the signal source block 118, the voltage controlled oscillator 106 loads the input modulation frequency (fm) on a microwave or millimeter wave (fo). That is, the voltage controlled oscillator 106 outputs the modulated signal fo + fm which is the sum of the fundamental wave fo and the modulation frequency fm. As the voltage controlled oscillator 106, for example, a signal source having a modulation bandwidth of 100 MHz in the 38.25 GHz band and an output power of 5 ㏈m may be used, and it is preferable that the voltage controlled oscillator 106 is implemented by an MMIC or Gunn diode. The power divider 105 is coupled to the output terminal of the voltage controlled oscillator 106, and distributes the modulation signal fo + fm from the voltage controlled oscillator 106 to transmit the modulated signal to the transmitter 117 and the receiver 119. Print each.

In the transmitting stage 117, the frequency multiplier 104 doubles the modulated signal from the power divider 105 of the signal source block 118 to twice the harmonics and outputs the doubled harmonic signal 2fo + 2fm. The driving amplifier 103 is connected to the output terminal of the frequency multiplier 104 and drives the RF gain of the doubled signal. The power amplifier 102 is connected to the output terminal of the driving amplifier 103 and amplifies the driving amplified signal. The transmit modulated signal output from the output terminal of the power amplifier 102 is radiated through the transmit antenna 101.

The frequency multiplier 104 of the present invention is made of MMIC and may have, for example, an input frequency band of 38 to 38.5 GHz and an output frequency band of 76 to 77 GHz. The frequency multiplier 104 preferably has excellent suppression characteristics of the input frequency and input / output matching characteristics with respect to the output frequency. The modulated signal thus multiplied by 2 is made of MMIC to correct the conversion loss in the frequency multiplier 104. For example, the driving signal 103 is applied to the output amplifier of the driving amplifier 103. The power amplifier 102 for power amplification fabricated in the MMIC is disposed. Preferably, the output power of the power amplifier 102 is 13 mA. It is to meet the output power specification of 10mW of current radar sensor. In the transmitting antenna 101, for example, output power of 10 mW is radiated. In this case, the transmit antenna 101 preferably uses a patch array antenna. The transmitting stage 117 is implemented by including a frequency multiplier 104, a driving amplifier 103, and a power amplifier 102, each made of a separate MMIC, or a frequency multiplier 104, a driving amplifier integrated with a single-chip MMIC. 103 and a power amplifier 102 may be implemented.

In the balance mixer, the balanced frequency mixer 107 uses the local oscillation signal fa generated by the local oscillator 108 to modulate the signal fo + fm from the power divider 105 of the signal source block 118. Up and down conversion are performed, and the converted first signal fo + fm + fa and the second signal fo + fm-fa are output to two different amplifiers 110 and 114 of the receiving end 119.

In the receiver 119, the downlink mixer 112 mixes the received signal 2fo + fb + 2fm with the first signal connected to the LO terminal through the first amplifier 110 of the receiver 119, and then mixes the mixed signal. Three signals (fo + fb-fa + fm) are sent to the intermediate frequency block 120. Here, the received signal is a signal received from the receiving antenna 109 and connected to the RF terminal of the downlink frequency mixer 112 through the low noise amplifier 111.

In the intermediate frequency block 120, the intermediate frequency mixer 115 mixes the third signal filtered only the desired frequency through the band pass filter 113 with the second signal connected to the LO terminal through the second amplifier 114. The mixed signal is sent to the IF output terminal. The intermediate frequency amplifier 116 is connected to the output terminal of the intermediate frequency mixer 115, amplifies the output signal fb from the intermediate frequency mixer 115, and converts the amplified beat signal into a digital signal processor of the radar sensor. To pass. Here, the bit signal refers to the reception frequency shift due to the Doppler effect.

The first amplifier 110, the low noise amplifier 111, and the downlink frequency mixer 112 of the receiver 119 may be made of individual MMICs or integrated into one one-chip MMIC. As the band pass filter 113 of the receiver 119, only a frequency of a desired band may be passed, and an RF band pass filter manufactured in a waveguide form may be used.

In the present invention, unlike the conventional homodyne transceiver, the modulated signal of the transmitting end 117 is not directly connected to the downlink mixer 112 of the receiving end 119, and the transmission modulated signal and the local oscillating signal of the receiving end 119 are not connected. For use separately, the local oscillation signal of the local oscillator 108 and the modulated signal from the voltage controlled oscillator 106 are up-converted and down-converted through the balanced frequency mixer 107, and then the converted first and second signals are converted. The signal is transmitted to the receiving end 119. In this case, the first signal and the second signal transmitted to the receiver 119 pass through the receiver 119 and the intermediate frequency block respectively through two different amplifiers 110 and 114 to correct the conversion loss of the balanced frequency mixer 107. Are connected to the LO terminals of the two frequency mixers 112 and 115 of 120. According to this configuration, the modulated signal of the transmitting end 117 in the RF transmission and reception module is separated without the influence of interference of the received signal.

In other words, in the present invention, a pair of frequencies in which an arbitrary local oscillation signal fa is balanced and mixed with a local oscillator and a modulation signal from the voltage controlled oscillator 106 of the transmitting end 117 is used. By connecting to the two frequency mixers 112 and 115 of the receiver 119, the signal interference between the transmitter and the receiver generated when the modulation signal from the voltage controlled oscillator of the existing transmitter is used directly is improved, thereby improving the transmission and reception separation characteristics. Let's do it. It is the transmission modulated signal 2fo + 2fm of the transmitter 117, the output signal first signal fo + fm + fa of the balanced frequency mixer 107, and the third frequency signal fo + fb down-converted by the signal. -fa + fm), the difference in the receiver signal is so large that it can reduce the interference between the transmitter and the receiver signal enough to improve the dynamic range performance of the receiver and to improve the detection range of the radar sensor can be implemented. .

For example, if the local oscillation signal fa is 1 kHz, the modulation signal fo + fm is 38.25 kHz and the transmission signal 2fo + 2fm is 76.5 kHz. And fb is the bit frequency which is the frequency deviation when the transmission signal is returned to the obstacle and the unit is MHz. In this case, 76.5 kHz + fb, which is a received signal, is input to the downlink mixer and downconverted by the first signal (fo + fm + fa) of 39.25 되어 to output 37.25 kHz + fb, and the intermediate frequency mixer 37.25 출력. The signal of fb is converted by the second signal fo + fm-fa, and amplified by an intermediate frequency amplifier, and transmitted to the digital signal processor as a bit signal.

For example, if the local oscillation signal fa is 37.25 Hz, the modulation signal fo + fm is 38.25 Hz and the transmission signal 2fo + 2fm is 76.5 Hz. In this case, 76.5 kHz + fb, which is a received signal, is input to the downlink mixer and downconverted by the first signal (fo + fm + fa) of 75.25 되어 to output a signal of 1 ㎓ + fb, and 1 in the intermediate frequency mixer is output. The signal of fb is amplified by an intermediate frequency amplifier and transferred to the digital signal processor as a bit signal after being converted by the second signal fo + fmfa.

The present invention can prevent the degradation of the reception sensitivity of the system, which is generated because the signal spectrum characteristic of the conventional RF transceiver, i.e., the signal from the transmitter to the receiver is relatively larger than the signal received through the receiving antenna. That is, the present invention has an advantage of improving the isolation of the RF transceiver module.

The above-described transmitting antenna and receiving antenna may select and use at least one of a parabola antenna, a lens antenna, a micro strip patch array antenna, and a horn antenna in addition to the patch array antenna.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and it is common in the art that various substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention. It will be evident to those who have knowledge of.

As described above, the RF transceiver module for the millimeter wave radar sensor according to the present invention can solve the problem of deterioration in reception sensitivity generated by the conventional homodyne RF transceiver module. That is, the reception sensitivity of the RF transceiver module for the radar sensor in the millimeter wave band can be improved by about 20 to 30 dB. In addition, it is a heterodyne RF transmission / reception module using MMIC, which can be easily applied to 77GHz band vehicle anti-collision radar sensor and adaptive autonomous driving control (ACC) system using this sensor. Can contribute.

Claims (12)

A transmitter for distributing a modulated signal generated by a voltage controlled oscillator, amplifying the modulated signal and radiating the amplified modulated signal through a transmit antenna; A balance mixing unit configured to up- and down-convert the modulated signal from the power divider using a local oscillation signal from a local oscillator, and output the up-converted first signal and the down-converted second signal; And Down-mixing the external signal received through the receiving antenna with the first signal through a downlink frequency mixer; mixing the downmixed third signal with the second signal through an intermediate frequency mixer; An RF transceiver module for a radar sensor comprising a receiving end for outputting a mixed signal of the third signal. The method of claim 1, And a first amplifier coupled between the balanced frequency mixer and the downlink frequency mixer installed in the balance mixer, and a second amplifier coupled between the balanced frequency mixer and the intermediate frequency mixer. The method of claim 2, The transmitter includes a frequency multiplier for multiplying the modulated signal from the power divider, a drive amplifier and a power amplifier for amplifying and outputting the output signal of the frequency multiplier to the transmitting antenna, wherein the frequency multiplier, the drive amplifier, and The power amplifier RF transceiver module for the radar sensor, characterized in that each is made of a separate MMIC. The method of claim 2 or 3, The receiver includes a low noise amplifier coupled between the receive antenna and the downlink frequency mixer, wherein the low noise amplifier, the first and second amplifiers, and the downlink frequency mixer are each made of separate MMICs. RF transceiver module. The method of claim 2, The transmitter includes a frequency multiplier for multiplying the modulated signal from the power divider, a drive amplifier and a power amplifier for amplifying and outputting the output signal of the frequency multiplier to the transmitting antenna, wherein the frequency multiplier, the drive amplifier, and The power amplifier RF transceiver module for the radar sensor, characterized in that the integrated one-chip MMIC. The method according to claim 2 or 5, The receiver includes a low noise amplifier coupled between the receive antenna and the downlink frequency mixer, wherein the low noise amplifier, the first and second amplifiers, and the downlink frequency mixer are integrated into one one-chip MMIC. RF transceiver module for radar sensors. The method of claim 1, And a band pass filter coupled between the downlink frequency mixer and the intermediate frequency mixer. The method of claim 1, Radar sensor RF transceiver module for amplifying a signal from the output of the intermediate frequency mixer, and further comprising an intermediate frequency amplifier for outputting the amplified signal as a bit signal. A millimeter wave FMCW radar sensor comprising an RF transceiver module, wherein the RF transceiver module comprises: A transmitter for distributing a modulated signal generated by a voltage controlled oscillator, amplifying the modulated signal and radiating the amplified modulated signal through a transmit antenna; A balance mixing unit configured to up- and down-convert the modulated signal from the power divider using a local oscillation signal from a local oscillator, and output the up-converted first signal and the down-converted second signal; And Down-mixing the external signal received through the receiving antenna with the first signal through a downlink frequency mixer; mixing the downmixed third signal with the second signal through an intermediate frequency mixer; Millimeter-wave FMCW radar sensor characterized in that it comprises a receiving end for outputting the mixed signal of the third signal. The method of claim 9, The RF transmission / reception module further includes a millimeter wave FMCW further comprising a first amplifier coupled between the balanced frequency mixer and the downlink frequency mixer installed in the balance mixer, and a second amplifier coupled between the balanced frequency mixer and the intermediate frequency mixer. Radar sensor. The method of claim 9, The RF transceiver module is a millimeter wave FMCW radar sensor further comprises a band pass filter coupled between the downlink mixer and the intermediate frequency mixer. The method of claim 9, The RF transceiver module includes a millimeter wave FMCW radar sensor further comprising an intermediate frequency amplifier for amplifying the signal from the output of the intermediate frequency mixer, and outputting the amplified signal as a bit signal.

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