Circuits, methods, apparatus, and systems for recovery of spread spectrum clock

A method for clock recovery from a spread spectrum signal having a center frequency modulated with a periodic modulation profile, said method comprising the steps of:

• comparing said spread spectrum signal to a recovered clock signal to produce a first error signal corresponding to said periodic modulation profile and a second error signal corresponding to one or more phase differences other than said periodic modulation profile;
• recording values based on said first error signal and producing a third error signal corresponding to a predicted periodic modulation of said spread spectrum signal based at least in part on recorded values;
• and
• producing said recovered clock signal in response to said second and third error signals.

An apparatus for clock recovery from a spread spectrum signal, said apparatus comprising:

• means for comparing a spread spectrum signal and a recovered clock signal, said spread spectrum signal having a center frequency modulated with a periodic modulation profile;
• means for producing a first error signal corresponding to said periodic modulation profile and a second error signal corresponding to one or more phase differences other than said periodic modulation profile;
• means for recording values to a frequency memory, said values based on said first error signal and for producing a third error signal corresponding to a predicted periodic modulation based at least in part on values recorded in said frequency memory;
• and
• means for generating said recovered clock signal in response to said second and third error signals.