Vector Modulator Based Leakage Cancellation Technique for CW Radar Transceiver Frontends

Millimeter-wave radar systems have been continuously developed until present day to accurately monitor the vital signs of humans non-invasively with recent research focused on enabling battery powered portable operation. To this end, the design of a low-voltage low-power V-band radar transceiver chip based on an advanced SiGe BiCMOS technology is presented in this paper. The LO-scalable chip equipped with BPSK and vector modulators consumes 60mA from a supply of 1.5 V. A low-power radar sensor built with this chip is operated at 59.2GHz in CW interferometry-mode to track sub-mm movements of targets vibrating with sub-Hz frequencies. The two main contributors of dc offset at the I/Q receiver output, LO-to-RX and TX-to-RX leakage signals, are canceled out by adjusting their phase using the modulators. This technique eliminates the dc offset up to 200mV and allows the measurement of sub-Hz frequency movements making it a viable option for vital signs detection.