An adaptive body-bias low voltage low power LC VCO

A novel LC VCO employing an adaptive body-bias is proposed for low power and low voltage high performance signal generation. By using the adaptive body-bias technique, the threshold voltage of the cross-coupled pair is reduced, and meanwhile the effective source-to-drain voltage and oscillation amplitude are increased, which improves the phase noise. In addition, the back-gate capacitances from the cross-coupled pair are used for frequency tuning which avoids quality factor deteriorations resulted from using extra tuning capacitance. In a standard 65nm CMOS process with a 0.4-V power supply, the proposed VCO achieves FOM of 189.8 with a phase noise of -122.5 dBc/Hz at 10MHz offset when operating at 24.25 GHz. The power consumption of the VCO is 0.94 mW.