A D-Band Active Down-Conversion Mixer with 80 GHz IF for FMCW Radar Frequency Extension

The development of D-band frequency extenders is one of the effective approaches toward radar miniaturization, facilitating the integration of radar and Light Detection and Ranging (LiDAR) in compact next-generation autonomous sensing platforms. This study presents a 150–157 GHz active down-conversion mixer, implemented in the 90 nm SiGe BiCMOS process. The circuit is based on a double balanced Gilbert cell mixer architecture, optimized to achieve high conversion gain and to function as a receive path frequency extender for 80 GHz frequency-modulated continuous-wave (FMCW) radar applications. The proposed mixer differs from conventional D-band receivers by providing an 80 GHz high-IF signal, rather than baseband output, to satisfy the receiver input frequency requirements of the radar chip. The circuit consists of a transconductance (Gm) stage, a switching (SW) stage connected by a differential inductor, and three transformers that convert the differential inputs/outputs to single-ended to ease on-wafer measurements. Measurements results show a peak conversion gain (CG) of 8 dB at 153 GHz, and an input-referred 1 dB compression point (P1dB) of -11.8 dBm. The down-conversion mixer consumes 46 mW power with 2.5 V of supply voltage, and chip area is 0.54 mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> including all GSG and DC pads.