A wideband LC-VCO with enhanced PSRR for SOC applications

Differential VCOs remain prone to common-mode power line disturbances. This limits their usefulness in SOC applications. In response, a fully integrated, 2.4-GHz 0.18-μm CMOS LC-VCO whose tank and switching core are isolated from supply noise is described. Using a balanced amplifier configuration, the effect of supply disturbances on the oscillator´s output are reduced by up to 40 dB. Further, this scheme does not compromise the VCO´s sensitivity allowing a 1-GHz (38%) tuning range. At a power dissipation of 11mW, the measured phase noise at 100-KHz offset from a 2.9-GHz carrier is -105 dBc/Hz.