A CMOS 76-81 GHz 2TX 3RX FMCW Radar Transceiver Based on Mixed-Mode PLL Chirp Generator

A fully integrated 76-81 GHz frequency-modulated continuous-wave (FMCW) radar transceiver (TRX) in 65nm CMOS is presented. Two transmitters (TXs) and three receivers (RXs) are integrated for MIMO processing. A 38.5 GHz mixed-mode PLL with reconfigurable loop bandwidth and frequency doubling scheme are employed to generate the reconfigurable FMCW chirp waveforms. Passive voltage-mode down-conversion is utilized to improve the RX linearity against TX leakage. A bottom-switching PA is proposed to realize the Bi-Phase modulation, and the magnetically-coupled resonator technique is widely used to effectively expand the link bandwidth. Measurement results show that the FMCW TRX could generate reconfigurable chirps with the bandwidth from 250 MHz to 4 GHz and the period from 600 us to 10 ms. The root-mean-square (RMS) frequency error is less than 251 kHz. The TX maximum output power is 13.4 dBm and is adjustable within 3 dB by reconfiguring its LDO output voltage. The RX achieves 15.3 dB noise figure and -8.5 dBm RF input-referred P1dB. Real-time experiments are carried out using the proposed TRX chip, in which the measured average distance error is 10 cm. The overall power consumption is 921mW with 2-TXs and 3-RXs powered on.