A Fully-integrated Doppler-assisted FMCW Radar with Low Hertz Range Noise Figure for Indoor Localization and Vital Sign Sensing

This paper presents a Doppler-assisted frequency modulated continuous wave (FMCW) radar that leverages the benefits of FMCW 's range resolution and Doppler's sensitivity for indoor applications. The Doppler mode reuses circuit blocks in the FMCW mode to reduce power consumption and area overhead. An "RF+LO+BB"combined noise figure (NF) analysis and optimization scheme is proposed to minimize the low-frequency noise. The radar employs a nested phase-locked loop frequency synthesizer with low phase noise and incorporates an optimized ΔTstep selection technique to improve chirp linearity. Designed in 55-nm CMOS technology, the radar achieves a NF of 32 dB at 10 Hz, with a chirp linearity of 0.0039% over a 3.52 GHz chirp bandwidth (BW), yielding a range resolution of 4.7 cm. It occupies an area of 12.7 mmsq and consumes 220 mA of current in the FMCW mode and 160 mA in the Doppler mode under a power supply of 3.3 V.