A 100-GHz Double-Sideband Low-IF CW Doppler Radar in 65-nm CMOS for Mechanical Vibration and Biological Vital Sign Detections

Based on the double-sideband low intermediate-frequency (IF) architecture, a 100-GHz CMOS radar transceiver is realized for non-contact small mechanical vibration and biological vital sign detections. A 50-GHz push-push frequency doubler with off-chip VCO is used to generate the 100-GHz local oscillator (LO) signal for the transmitter (TX) and the receiver (RX). Injected by a 40-mV 1-kHz sinusoidal IF carrier input, the TX achieves a relatively constant 4-dBm output power over 93–105 GHz. Under a -36-dBm RF input from 95 to 104 GHz, the RX achieves < 1 dB I/Q amplitude imbalance, < 1° phase mismatch and 236–341 mV quadrature IF differential output. With two horn antennas, the radar system successfully detects the mechanical vibration with 0.4-mm displacement, human heartbeat, and a bullfrog’s vital sign at 103 GHz. Fabricated in a 65-nm CMOS, the transceiver chip has a size of 1.8 mm² and consumes 341 mW from a 1.2-V power supply.