A constant-current-controlled class-C VCO using a self-adjusting replica biasing scheme

This paper proposes a constant-current-controlled class-C VCO using a self-adjusting replica biasing scheme. The proposed class-C VCO can maintain constant current which is more robust over a variation of low gate bias of a cross-coupled pair comparing to a traditional current mirror. The proposed VCO is implemented in a 0.18-μm CMOS process. The measured phase noise is -121.3dBc/Hz at 1MHz offset with a power dissipation of 4.8mW while oscillating at the frequency of 4.9GHz. The figure-of-merit is approximately -189 dBc/Hz.