Patent ID: 7279995

Claim:
A circuit comprising: a phase detector adapted to receive a reference signal and a feedback signal and provide a first output signal based on a phase difference between the reference signal and the feedback signal; a charge pump, coupled to the phase detector, adapted to provide a second output signal based on the first output signal; a loop filter, coupled to the charge pump, adapted to filter the second output signal; a voltage controlled oscillator, coupled to the loop filter, adapted to provide a third output signal based on the second output signal, wherein the voltage controlled oscillator comprises a ring oscillator and further wherein the ring oscillator comprises a plurality of series connected inverters; a phase comparator circuit having a first input coupled to an output of one of the series connected inverters, a second input coupled to a reference frequency source, and an output; a voltage control circuit having a input coupled to the output of the phase comparator circuit and an output coupled to at least one of the series connected inverters, the voltage control circuit being adapted to provide a control voltage to at least one of the series connected inverters; and a divider circuit, coupled to the voltage controlled oscillator and the phase detector, adapted to provide frequency reduction to the third output signal to a desired level and provide the feedback signal to the phase detector.