300-GHz Double-Balanced Up-Converter Using Asymmetric MOS Varactors in 65-nm CMOS

A 270-300-GHz double-balanced up-converter fabricated in 65-nm CMOS is presented. The up-converter is the first to employ accumulation mode MOS asymmetric varactors (ASVARs) as mixing devices. A power-splitting-transformer hybrid is utilized to improve differential signal isolation. The up-converter achieves the maximum conversion gain (CG) of -11.2 dB and the output 1-dB compression point (OP _{\text {1,dB}} ) of -6.2 dBm including the losses of input and output baluns added for measurements. The maximum CG and OP _{\text {1,dB}} are the highest among up-converters operating near 300 GHz in CMOS and III-V transistors. The 3-dB bandwidth of CG is \sim 25 GHz, which makes the up-converter suitable for high data-rate communication.