A 60-GHz CMOS direct-conversion Doppler radar RF sensor with clutter canceller for single-antenna noncontact human vital-signs detection

This paper presents a 60-GHz CMOS direct-conversion Doppler radar RF sensor with a quasi-circulator (QC) and a clutter canceller circuit for single-antenna noncontact human vital-signs detection. A high isolation QC is designed to provide better detection sensitivity for the tiny vital-signs detection for the single-antenna Doppler radar architecture. The clutter canceller performs cancellation for the transmitting leakage power from the circulator and the background reflection clutter to enhance the detection sensitivity of weak vital signals. The measurement shows that the total transmitting power is 3 dBm while the conversion gain of the sub-harmonic receiver is 10.5 dB. In the human vital-signs detection measurement, at a distance of 75 cm, the detected heartbeat (1–1.3 Hz) and respiratory (0.35–0.45 Hz) signals can be clearly observed. The RF sensor is fabricated in 90-nm technology with a chip size of 2 mm × 2 mm and a consuming power of 217 mW. The presented CMOS vital-signs Doppler radar RF sensor will be very useful for the wireless remote physiological monitoring healthcare system and the tiny vibrations detection applications.