425-to-25-GHz CMOS-Integrated Downconverter

An integrated 425-GHz radio frequency (RF) to 25-GHz intermediate frequency (IF) second-order subharmonic downconverter, including an on-chip 8X local oscillator (LO) signal multiplier circuit that provides ~1 dBm at 200 GHz from an externally applied 25-GHz signal, and a 25-GHz IF amplifier, achieves a conversion gain of 6.7 dB and a noise figure of ~17 dB. The downconverter consumes 190 mW of dc power. Compared to the previously reported CMOS and SiGe HBT receivers/downconverters operating around 400 GHz and above, the downconverter achieves ~18-dB lower single side band noise figure. Finally, a passive switching mixer can have an available output noise spectral density less than kT, which can make its NF less than its conversion loss.