Patent ID: 6285219
Filing Date: 2001-09-04
Classification: H03D,H03L,H04L

Abstract:
A dual mode phase and frequency detector for use with a charge pump and a loop filter, the charge pump being adapted to adjust charging of the loop filter to adjust a VCO for generating a digital clock, the dual mode phase and frequency detector comprising:a phase and frequency detector arranged to receive the digital clock for tracking a reference clock signal, the phase and frequency detector being configured to generate control signals in response to the digital clock and the reference clock signal, the control signals being adapted to control charging or discharging of the loop filter by the charge pump when the phase and frequency detector is operating in a phase and frequency detector mode responsive to a mode control signal; anda delay element couple to receive the mode control signal and one of the control signals from the phase and frequency detector for generating an auxiliary control signal in response to the VCO digital clock, the first delay element generating the auxiliary control signal when the phase and frequency detector is operating in a phase detector mode responsive to the mode control signal, wherein the auxiliary control signal and the control signals are adapted to control the charge pump that charges or discharges the loop filter for adjusting the digital clock of the VCO when the phase and frequency detector is operating in the phase detector mode.