Method and apparatus for jitter reduction in phase locked loops

A system comprising:

• a phase-frequency detector (PFD), the PFD coupled to receive a buffered feedback clock and a buffered reference clock and at least one delayed feedback clock and at least one delayed reference clock;
• a charge pump, the charge pump coupled to receive an up signal and a down signal from the PFD and to generate a control voltage correction in response;
• and
• a voltage controlled oscillator (VCO), the VCO coupled to the charge pump to receive the control voltage correction,
• wherein the charge pump is 1/N the strength of a conventional charge pump adequate to generate an appropriate control voltage to the VCO based on receiving a single up signal or down signal within one cycle of the reference clock, the charge pump generating N control voltage corrections each being 1/N the amplitude of the appropriate control voltage of the conventional charge pump, thus reducing glitches on the N control voltage corrections and reducing jitter to the VCO, wherein N is greater than one.

A microcircuit comprising:

• a phase-frequency detector (PFD), the PFD coupled to receive a buffered feedback clock and a buffered reference clock and at least one delayed feedback clock and at least one delayed reference clock;
• a charge pump, the charge pump coupled to receive an up signal and a down signal from the PFD and to generate a control voltage correction in response;
• and
• a voltage controlled oscillator (VCO), the VCO coupled to the charge pump to receive the control voltage correction,
• wherein the charge pump is 1/N the strength of a conventional charge pump adequate to generate an appropriate control voltage to the VCO based on receiving a single up signal or down signal within one cycle of the reference clock, the charge pump generating N control voltage corrections each being 1/N the amplitude of the appropriate control voltage of the conventional charge pump, thus reducing glitches on the N control voltage corrections and reducing jitter to the VCO, wherein N is greater than one.