Patent ID: 7932757

Claim:
An apparatus comprising: a voltage controlled oscillator (VCO); a phase frequency detector (PFD) to provide a phase comparison operation; a loop filter to generate a control voltage to lock the VCO to a desired operating frequency; a charge pump to generate an output signal to the loop filter in response to at least one of an UP pulse and a DOWN pulse; a sampling switch, coupled to an input of the loop filter and an output of the charge pump, and characterized by a sampling interval; a sampling switch controller to adaptively control a width of the sampling interval to mitigate effects of leakage current from the charge pump by closing the sampling switch in advance of the phase comparison operation and opening the sampling switch when the phase comparison operation is completed, wherein the sampling switch controller is configured to receive an advanced reference clock signal and an advanced divider clock signal and to control the sampling switch to close just before the phase comparison operation by the PFD and to open just after the phase comparison operation thereby ensuring that all error charge has been sampled onto the loop filter while simultaneously minimizing a duration for which the loop filter is connected to potential leakage paths in the charge pump; and a programmable delay coupled to the PFD and configured to receive the advanced reference clock signal and to delay the advanced reference clock signal to produce a reference clock signal, wherein the PFD is configured to perform the phase comparison operation in response to the reference clock signal.