A 30-mW D-Band High-Sensitivity Self-Injection-Locked Radar Sensor with Integrated SIW Antenna in 70-nm GaAs pHEMT Technology

This paper presents a D-band GaAs self-injection locked (SIL) radar sensor featuring an integrated frequency differentiator and an on-chip substrate integrated waveguide (SIW) monopole antenna for non-contact vital sign detection. The integrated sensor is implemented in an advanced 70-nm GaAs pHEMT technology (PP07) with a peak <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$f_{T}$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$f_{\text {max }}$</tex> of 160 and 360 GHz, respectively. The oscillator achieves a center frequency of 138.3 GHz with a very low DC power consumption of 30 mW under a 2-V supply. The overall chip area, including the antenna, is only 1.732 mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>. Experimental results demonstrate the ability of the sensor to accurately detect respiration and heart rates at distances of up to 1.05 meters, with measurements closely matching the ground truth obtained using reference devices. Additionally, the results validate the system's performance even in challenging conditions of significant signal attenuation due to the operating frequency mismatch between the proposed sensor and the measuring components, achieving a combination of ultra-compact design, high sensitivity, and power efficiency.