Patent ID: 7719331

Claim:
A device comprising: a phase frequency detector that receives an input signal and a feedback output signal, that compares phase and frequency of the input signal with those of the feedback output signal and that outputs a comparison result output signal indicative of the result of comparison; a charge pump circuit that receives the comparison result output signal from said phase frequency detector and that generates a control voltage in accordance with the result of comparison in said phase frequency detector; a voltage-controlled oscillator that receives said control voltage and that generates an output signal of a frequency in accordance with said control voltage, said output signal of said voltage-controlled oscillator, or a frequency-divided version of said output signal, being supplied directly as said feedback output signal to said phase frequency detector; and a circuit unit which produces at least one control signal relative to an offset characteristic of said charge pump circuit and supplies the at least one control signal to said phase frequency detector, the phase frequency detector responding to the at least one control signal to adjust a pulse width of the comparison result output signal in said phase frequency detector.