A 180-GHz Passive Integrated SiGe Down-Conversion Mixer with Low Loss and a Broadband Rat-Race Coupler Design

This paper reports on the design and layout of a 180-GHz down-conversion mixer in a 130nm SiGe BiCMOS technology. The mixer has a single-balanced passive core, with diode-connected npn heterojunction bipolar transistors as mixing devices, a common-collector output buffer, a broadband rat-race coupler, and an LO driver for measurement. The mixer has a minimum conversion loss of 6 dB over a broad LO-RF bandwidth of 50 GHz, and an input-referred 1-dB compression point of -7 dBm. It requires only -30 dBm of LO power with the integrated LO driver. The circuit has a dc power consumption of 0.1 mW for the mixer and 2.7 mW for the output buffer. The circuit occupies a total area of 0.88 mm2.