A D-Band GaAs pHEMT 2T1R Super-Regenerative Oscillator-BasedSensor Array Using Quench-Controlled Phase-Shifting TechniqueFor Multi-Target Vital Sign Detection

This work presents the first super-regenerative oscillator (SRO)-based sensor array capable of beam–null controlled vital sign detection, extending beyond all previously reported single-element SRO implementations. A D-band 2T1R SRO sensor array is implemented in a 70-nm GaAs pHEMT technology, where two externally quenched SRO transmitters operate with a shared harmonic-mixer receiver. By introducing a controlled phase difference between synchronized quench waveforms, the effective excitation phase between the two radiating elements can be precisely adjusted, enabling two-element array factors with main-beam directions at -1◦ and 28◦ despite an inherent 108◦ geometric phase offset due to chip geometry. The prototype reliably detects 0.5-Hz actuator vibrations at a distance of 1.3 m, recovers human respiration (0.30–0.40 Hz) and heartbeat (1.30–1.60 Hz) at 1 m distance, and demonstrates angular selectivity by enhancing the intended subject while suppressing off-axis targets.