Design of a 100-GHz Double-Sideband Low-IF CW Doppler Radar Transceiver for Micrometer Mechanical Vibration and Vital Sign Detection

This article presents a fully integrated 100-GHz continuous-wave Doppler radar transceiver with the double-sideband low-intermediate-frequency (IF) architecture for mechanical vibration and vital sign detection. Fabricated in a 65-nm CMOS process, the whole radar chip transceiver consumes 262 mW with a size of 0.9 mm $\times2.0$ mm. Instead of utilizing a fundamental 100-GHz voltage controlled oscillator (VCO) in the chip, a push-push frequency doubler with the 50-GHz external source is adopted to drive the transceiver. Under a dedicated design on the system architecture and circuit blocks, the chip could transmit 4-dBm saturated power ($P_{\mathrm {sat}}$ ) over 93-105 GHz with a 40-mV 1-kHz IF carrier and achieve good I/Q performance of phase mismatch <; 1° and amplitude mismatch <; 1 dB over 95-104 GHz. With a-36-dBm RF input from 99 to 104 GHz, the IF differential output amplitude varies from 470 to 680 mV. To validate the detection ability, a probe-station-based test setup is proposed. Benefiting from the short wavelength at 103 GHz, this radar system successfully detects the mechanical vibration of 1-$\mu \text{m}$ displacement from 1.5 m, the human vital-sign signal from 2 m, and even a small bullfrog's hybrid respiratory motion from 0.6 m. To the best of our knowledge, this is the first 100-GHz CMOS Doppler radar transceiver chip with the low-IF architecture for the biological vital sign detection.