Method and apparatus for smoothing jitter generated by byte stuffing
AssigneeApplied Micro Circuits Corporation
InventorsYehuda AZENKOT, Timothy P. WALKER
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Abstract
Systems and methods for smoothing jitter generated by byte stuffing. A frequency synthesizer comprises a smoothing logic coupled with a PLL. The smoothing logic is configured to modify a phase error signal generated by a phase frequency detector into a distributed phase error signal that spread over multiple clock cycles. The distributed phase error signal is used to drive a DCO. The smoothing logic may comprise a ramping logic operable to generate a series of ramping values to substitute a phase difference in the phase error signal. The phase difference may correspond to a stuffing byte.
Claims22
A method of jitter attenuation, said method comprising:
- providing an input signal to a phase lock loop (PLL);
- detecting a phase difference between said input signal and a feedback signal of said PLL and generating a first phase error signal;
- and
- converting said first phase error signal to a second phase error signal comprising a smaller average gradient than said first phase error signal.
An integrated circuit for frequency synthesis, said integrated circuit comprising:
- a phase locked loop (PLL) comprising a phase frequency detector configured to output a phase error signal based on comparison between an input signal and a feedback signal of said PLL;
- and
- smoothing logic coupled to said phase frequency detector and configured to distribute a phase step in said phase error signal to a plurality of clock cycles.
A method of frequency synthesis, said method comprising:
- providing a gapped signal to a phase locked loop (PLL);
- detecting a phase difference between said gapped signal with a feedback signal of said PLL to generate a first phase error signal;
- converting said first phase error signal to a second phase error signal having a smaller average gradient than said first phase error signal;
- and
- generating an output signal of said PLL responsive to said second phase error signal, said output signal having said output frequency.
Dependencies are inferred from the claim text.