300-GHz 2nd-Order Subharmonic Upconversion Mixer Using Symmetric MOS Varactors in 65-nm CMOS

A 2nd-order subharmonic upconversion mixer with an intermediate frequency of 150 GHz and radio frequency (RF) of 290 GHz that employs accumulation mode MOS symmetric varactors is demonstrated in 65-nm complementary metal-oxide-semiconductor. A transformer-based hybrid is utilized to improve port isolation. The mixer achieves the maximum conversion gain of -16 dB including the losses (~2 dB total) of input and output baluns added for measurements. The local oscillator power at 70 GHz was 11.5 dBm and the 27-GHz 3-dB bandwidth spans between 284 and 311 GHz. The -11.6-dBm output 1-dB compression point from a single mixer is the highest among that for the 2nd-order subharmonic mixers with RF of ~300 GHz fabricated in any process technologies.