Dual Path Timing Jitter Removal

摘要

A gap detector detects when a phase difference between a feedback signal and a clock signal is larger than a gap threshold. If the phase difference is larger than the gap threshold, then the phase difference is modified by subtracting a gap value from the phase difference. If the phase difference is less than the threshold, the phase difference is not modified. A loop filter receives and filters the modified or unmodified phase difference and controls an oscillator. An accumulator circuit accumulates the modified phase difference and supplies a phase adjust signal. A low pass filter receives the phase adjust signal and supplies a filtered phase adjust signal that is used to slowly adjust the output of the oscillator.

主权项

1. An apparatus comprising:
a phase detector to supply a phase difference between an input clock signal and a feedback signal; a gap detector coupled to the phase detector to detect when the phase difference is larger than a gap threshold; a first circuit responsive to the detected difference being larger than the gap threshold to supply a modified phase difference in which a gap value is subtracted, the first circuit being responsive to the detected difference being smaller than the gap threshold to supply the phase difference; a loop filter coupled to an output of the first circuit to filter the output of the first circuit; and an oscillator controlled to supply an oscillator output signal according to the loop filter output.