A 9-31-GHz subharmonic passive mixer in 90-nm CMOS technology

A subliarmonic down-conversion passive mixer is designed and fabricated in a 90-nm CMOS technology. It utilizes a single active device and operates in the LO source-pumped mode, i.e., the LO signal is applied to the source and the RF signal to the gate. When driven by an LO signal whose frequency is only half of the fundamental mixer, the mixer exhibits a conversion loss as low as 8-11 dB over a wide RF frequency range of 9-31 GHz. This performance is superior to the mixer operating in the gate-pumped mode where the mixer shows a conversion loss of 12-15 dB over an RF frequency range of 6.5-20 GHz. Moreover, this mixer can also operate with an LO signal whose frequency is only 1/3 of the fundamental one, and achieves a conversion loss of 12-15 dB within an RF frequency range of 12-33 GHz. The IF signal is always extracted from the drain via a low-pass filter which supports an IF frequency range from DC to 2 GHz. These results, for the first time, demonstrate the feasibility of implementation of high-frequency wideband subliarmonic passive mixers in a low-cost CMOS technology.