Patent ID: 7629854

Claim:
A phase locking method, the method comprising: receiving a reference signal and a feedback signal; detecting a phase difference between the reference signal and the feedback signal; representing the phase difference with a current signal; processing the current signal using a switch-capacitor circuit comprising a sampling capacitor, a load capacitor, and a plurality of switches; using an output of the switch-capacitor circuit to control a variable oscillator; generating the feedback signal using an output of the variable oscillator; generating a plurality of timing signals based on a timing of the reference signal including generating a first timing signal and a second timing signal for defining a sampling phase and a charge-transfer phase, respectively, wherein the sampling phase is centered approximately at a first edge of the reference signal; controlling said switches using said timing signals including turning on a sampling switch and turning off a charge-transfer switch during a sampling phase to allow the sampling capacitor to integrate the current signal, and turning off the sampling switch and turning on the charge-transfer switch during a charge-transfer phase to allow the charge stored on the sampling capacitor to transfer to the load capacitor; and using an amplifier to facilitate the charge transfer during the charge-transfer phase.