A Monolithic InGaP/GaAs HBT Front-End Architecture for Continuous-Wave Doppler Radar Sensors in Omnidirectional Moving Target Detection

This paper proposes a cost-effective Doppler radar front-end architecture based on InGaP/GaAs heterojunction bipolar transistor (HBT) technology for continuous-wave (CW) omnidirectional moving target detection. The compact front-end architecture integrates three core components—a mixer, a power divider, and an oscillator—on a monolithic microwave integrated circuit (MMIC). The power divider (PD) provides both the transmit signal and the local oscillator (LO) signal for the mixer. The oscillator employs a conventional cross-coupled configuration, achieving a phase noise of −119.5 dBc/Hz at 1 MHz offset from the carrier frequency of 5.81 GHz. The compact transceiver achieves an area of 0.5 × 0.55 mm² while maintaining greater than 18 dB conversion gain over the entire 5.725–5.875 GHz ISM band. The total power consumption is less than 33 mW with a 3.3 V supply. Experimental measurements on two DRS testing systems demonstrated that the system's transmission power was approximately −2 dBm, and omnidirectional moving human presence detection tests indicated a horizontal detection distance greater than 4 meters when the radar system was mounted at a height of 3 meters.