A SiGe-based broadband 140–170-GHz downconverter for high resolution FMCW radar applications

A D-Band downconverter implemented in a 130-nm SiGe BiCMOS technology is presented. The mixer is based on a double-balanced Gilbert cell topology with emitter-follower based output IF buffers. The chip includes an integrated 3-stage LO buffer and RF/LO LC-baluns for single-ended on-wafer measurements. Measurements show a peak conversion gain (CG) of 11 dB at 170 GHz, and an input-referred 1 dB compression point of -13 dBm. By employing wideband impedance matching structures at the RF/LO inputs, a state-of-the-art 3-dB CG bandwidth of 30 GHz (140-170 GHz, limited by the equipment bandwidth) is achieved, which is essential for implementing high resolution FMCW radars. Second version of the receiver includes a 2-stage RF amplifier and shows a measured CG of 21 dB. The mixer core consumes a DC power of 115mW.