A 20GHz VCO and frequency doubler for W-band FMCW radar applications

This paper presents a low-noise Colpitts VCO with transformer-based resonator and a 20-to-40GHz frequency doubler for use in 76∼77GHz long-range radar and 77∼81GHz short-range radar transceivers. To reduce supply pushing and AM-to-PM noise conversion in the high-gain VCO, a differentially tuned, transformer-coupled varactor is used. Implemented in 0.12-μm SiGe BiCMOS technology, the VCO and doubler achieve an 11% continuous tuning range from 37.5–42GHz, and a phase noise between −103 and −106dBc/Hz at 1MHz offset from the 40GHz carrier.