Patent ID: 6803830
Filing Date: 2004-10-12
Classification: H03L

Abstract:
A phase-locked loop comprising:a voltage-controlled oscillator, a control voltage applied to said voltage-controlled oscillator, said control voltage provided by a phase/frequency detector as a function of the difference between the frequency of a reference signal and the output frequency of the voltage controlled oscillator, the oscillator including as a frequency-influencing circuit element a varactor whose capacitance value is variable over a fine adjustment range by the control voltage for altering the output frequency; a variable capacitance connected in parallel to said varactor responsive to a change in the frequency (fâ€²ref) of said reference signal, the value of said capacitance being adjustable as a function of said control voltage output by said phase/frequency detector; and a control logic responsive to said control voltage and selected periodic cycles of said frequency of said reference signal to control variation of said variable capacitance.