Patent ID: 6803827
Filing Date: 2004-10-12
Classification: H03L

Abstract:
A phase-locked loop system for a coarse and fine tunable oscillator comprising:a phase detector responsive to the phase of an output signal of a tunable oscillator and the phase of a reference signal to provide an output signal representative of a difference in phase between said output signal and the reference signal; a loop filter, responsive to said output signal representative of the difference in phase, for providing a fine control signal to a fine control of the tunable oscillator to drive the frequency of the output signal of the tunable oscillator toward the frequency of said reference voltage; and an accumulator circuit for digitally storing the present state of a coarse control signal of the tunable oscillator and responsive to said fine control signal for digitally updating the state of the coarse control of the tunable oscillator to drive the frequency of the output signal of the tunable oscillator towards the frequency of the reference signal.