A SiGe-based wideband 220–310-GHz subharmonic receiver front-end for high resolution radar applications

This paper presents a J-Band (220-325 GHz) subharmonic receiver front-end implemented in a 130 nm SiGe BiCMOS technology. The receiver chip includes integrated LO amplifiers and wideband Marchand baluns at the RF and LO ports for single-ended measurements. The subharmonic down-conversion mixer is based on a novel topology having a Gilbert cell with stacked switching quads, which are fed by equal-phase local oscillator signals. A very wideband operation is achieved by directly matching the RF input signal to the emitter terminals of the switching quad and not using a transconductance stage. On-wafer measurements of the receiver show a peak conversion gain of 11 dB, a minimum double side band noise figure of around 16 dB and a simulated input compression point of -7 dBm, while consuming a total DC power of 160 mW. The chip demonstrates the highest 3-dB conversion gain bandwidth and compression point for Si-based receivers operating above 200 GHz.