US Patent 7863991 Wide range/high speed low power CMOS VCO

A VCO circuit having low jitter and low PSS (power supply sensitivity). The VCO circuit includes a first ring oscillator stage, a second ring oscillator stage coupled to the first ring oscillator stage, and a VCO input coupled to both the first ring oscillator stage and the second ring oscillator stage for receiving a control voltage. Each of the first ring oscillator stage and the second ring oscillator stage further includes a CMOS inverter with a plurality of cross coupled transistors to implement oscillation of the VCO circuit.