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Non-contact vital sign detection using 60-GHz radar offers various advantages such as higher sensitivity and smaller antennas compared to lower-frequency systems, however, the respiration amplitude comparable to wavelength causes strong non-linear phase modulation, and relatively small heartbeat amplitude results in detection difficulty. In this paper, theoretical analysis and simulation of 60-GHz detection are provided to address these issues. Both shallow and deep breathings are tested in the experiments, and the detection technique monitoring both the fundamental and second harmonic of respiration is proposed. The phenomena explained in the work can be applied to many millimeter-wave Doppler radar applications where target displacement is comparable to or larger than the wavelength to ensure robust detection.Index Terms -Doppler radar, frequency measurement, microwave sensor, medical signal detection.

A 60 GHz micro-radar in 90 nm CMOS for non-contact vital sign and small vibration detections was designed and tested. A quadrature receiver embedded in the indirect up-and down-conversion architechture solves the null detection point issue and increases the robustness of the millimeter wave system. In the 60 GHz core, lumpedelement-modeled passive components are extensively used to achieve a compact layout (0.73 mm 2 ), and a 36 dB downconversion gain at 55 GHz. Using low-cost single-patch PCB antennas, flip-chip packaging of the CMOS chip demonstrates high level of system integration. First pass success is achieved as the human heartbeat and a small mechanical vibration with a displacement of 20 μm can be detected at 0.3 m away. With a roughly one-tenth patch antenna size compared to previously reported works, the 60 GHz CMOS integrated micro-radar can be readily embedded in various portable devices to detect vary small vibrations and used for many applications.Index Terms -CMOS, Doppler radar, flip chip, millimeter wave integrated circuits, medical signal detection, patch antennas, sensor systems, frequency measurement.

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