9.4 A 145GHz FMCW-Radar Transceiver in 28nm CMOS

Abstract

Indoor radar applications detecting people, vital signs and minute gestures require a high range resolution. This paper presents a 145GHz FMCW radar transceiver with on-chip antennas in 28nm bulk CMOS. An RF bandwidth of 13GHz yields an 11mm range resolution, and the high RF carrier permits greater velocity and MIMO-angular resolution. An external chirp signal at 16.1GHz is upconverted to 145GHz via a cascade of two frequency triplers in the RX and TX. For MIMO operation, a central chirp signal from a sub-sampling PLL integrated in 28nm CMOS [1] is distributed to multiple TRX chips on a PCB, eliminating mm-wave signal routing. The radar operates over a 0.15-to-10m range using fast sawtooth chirps of 5-to-$50 \\mu \\mathrm {s}$ duration. The beat frequency at IF fits between 400kHz and 15MHz. The on-chip TX leakage produces a strong beat near DC, suppressed via active highpass filtering. However, group delays of the PA and LNA can shift the beat into the RX passband. This is overcome by delaying the 16.1GHz RX chirp on chip. The chip dissipates 500mW in continuous mode, with the option of a low-power, duty-cycled FM transmission mode (for close ranges) enabled via fast powering built into the transceiver.