Research And Design Of Key Technologies Of Millimeter-Wave Radar Receiver For Automotive

Low-cost,highly integrated CMOS millimeter-wave vehicle radar has become a current research hotspot due to its wide detection range and high resolution.Highly automotive needs to achieve detection that can cover short,medium,and long-range targets.The 77 GHz FMCW radar has a wider sweep BW and better range resolution to achieve real-time and accurate collision warning in high-speed ACC.In order to achieve long-range（150 m）target detection,77 GHz radar can use phased array technology to effectively increase the maximum detection range of the target.For the detection of short-range targets used in automotive such as APS,the radar needs to have better divergence.Therefore,the 24 GHz radar is mostly used for short-range target detection due to its larger 3 d B beam width,and because short-range radars need to be installed in multiple locations on the vehicle.The 24 GHz radar with lower power consumption and cost is more suitable for short-range radars.（1）In order to achieve more accurate target resolution and longer detection distance,this paper designs a 77 GHz eight-element phased array mid-range and long-range radar receiver based on 55-nm CMOS technology.In order to achieve a wider detection range and lower DC power,this paper designs a 24 GHz dual-mode short-range radar receiver.（2）This paper completes the key technology research and design of 77 GHz phased array mid-range and long-range radar receiver chip.Firstly,according to the transformer pole theory,the resonance peak control technology is adopted to increase the bandwidth.The three-turn anti-phase coupling input balun effectively improves the equivalent transconductance of the circuit.A 77 GHz three-level broadband LNA has been completed.Test results show that this broadband LNA can obtain a 3 d B bandwidth of 15 GHz,with a gain of 11.2 d B,NF and IP1d B of 6.7 d B and-7 d Bm,respectively.The power consumption is 41 m W.This article has completed the design of LNA and Mixer for 77GHz radar receivers.LNA uses peak resonance control technology to increase bandwidth.The post-simulation results show that the 77 GHz LNA can obtain a peak gain of 22 d B,a NF of6.7 d B,and a gain of more than 18.1 d B in a bandwidth of 76～81 GH at TT corner.The down mixer in the 77 GHz vehicle radar adopts an active quadrature double-balanced structure,using dynamic current injection technology and resonance peak control technology.The post-simulation results show that the CG is greater than 8.0 d B in the 76～81 GHz bandwidth,and the noise figure of 13.6～19.2 d B can be obtained at 500 KHz～10 MHz intermediate frequency.Secondly,the other modules of 77 GHz eight-element phased array radar are designed,including tripler and phase shifter.The post-simulation results show that the insertion loss of the tripler is only-7.5～-6.5 d B.The phase shifter adopts a 4-bit switch type passive phase shifter structure.The simulation results show that the RMS phase error of this 76～81 GHz 4bit phase shifter is less than 9 deg under five corners,the optimal RMS phase error is only 1.5 deg.Thirdly,a 77 GHz eight-element phased array radar system is designed.Using the process library transmission line to design the 8-1 Wilkinson power combiner.The post-simulation shows:the peak CG of the single-element receiver can reach 22 d B,the CG is greater than 15d B in the76～81 GHzbandwidth.The input P1d B at the highest gain is-17 d Bm,and the optimal noise figure at the 10 MHz IF is 7.5 d B,The optimal NF at 500 KHz intermediate frequency is 8.5 d B.The peak-to-null of the receiver array is greater than 20 d B,and the peak-to-peak is greater than 10.5 d B.（3）This paper completes the key technology research and tape-out of the short-range 24GHz dual-mode radar receiver chip.Firstly,the 24 GHz radar uses a PCB antenna that can achieve a beam-width_{3 d B} of±40°.So the isolation between the transceivers is only 20 d B,and the 24 GHz short-range radar has a lower intermediate frequency.Therefore,the impact mechanism of the transmitter leakage of millimeter wave short-range radar on the receiver flicker noise is analyzed.Secondly,this paper design a RXFE for 24 GHz short-range radar.In order to optimize the flicker noise,a passive Mixer is used.In order to compensate for the receiver link gain,a common source LNA is added.The LNA and Mixer are combined through a 2-4 transformer design.An 8-bit DAC for 24 GHz short-range dual-mode radar is designed to provide different bias voltages for the two modes and process corner.Finally,a 24 GHz dual-mode automotive radar chip is designed and taped out.The post-simulation results show that this radar receiver can obtain CG of 15.8 d B in the FMCW mode,the CG is greater than 13 d B in the 23-24.25 GHz working bandwidth,and the NF is12.5 to 17.5 d B in the 8.3 KHz～166 KHz IF range.Indoppler mode,the CG can reach 16.9 d B,the NF at the IF of 10 Hz～1 KHz is 15.2～33d B,the IP1d B is better than-14 d Bm,and the DC power of a single RX element is only 44 m W.The above-mentioned 24 GHz short-range radar has been taped out,chip testing is now underway,and the 77 GHz radar chip has been put into production.Combine two millimeter-wave radars covering long,medium and short-range detection to meet the hardware requirements of automotive.