A novel variable inductor-based differential Colpitts VCO design with 17% frequency tuning range for 30 and 60 GHz applications

A 30 GHz variable inductor (VID) based differential Colpitts VCO is presented in this paper. The integration of the VID in the VCO tank widens the tuning range (TR) of the VCO. As the result, this VCO design achieves 17% TR between 28.3 and 33.5 GHz, a recorded −101.4 dBc/Hz phase noise at 1 MHz offset, and 4 dBm output power. This VCO was fabricated in a 130 nm SiGe BiCMOS process and the circuit occupies 350 µm × 405 µm die area.