Prediction based digital control for fractional-n plls
AssigneeInternational Business Machines Corporation
InventorsHERSCHEL A. AINSPAN, MARK FERRISS, DANIEL J. FRIEDMAN, ALEXANDER V. RYLYAKOV, BODHISATWA SADHU, ALBERTO VALDES GARCIA
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Abstract
Methods and systems for phase correction include determining a phase error direction and generating a prediction for the phase error based on a sigma-delta error. It is determined whether the prediction agrees with the determined phase error direction. If the prediction does not agree, a phase correction is adjusted in accordance with the predicted phase error.
Claims19
A fractional-N digital phase-locked loop (PLL), comprising:
- a prediction module, configured to generate a predicted phase error based on a sigma-delta error and to output a phase error correction if the predicted phase error disagrees with an early/late signal based on a reference signal and a feedback signal;
- an integer divider, configured to divide by an integer value N a frequency of a phase-corrected multiple of the reference signal that is based on the output of the prediction module;
- and
- a sigma-delta module, configured to change the integer value N in accordance with a non-integer divide ratio.
A fractional-N hybrid phase-locked loop (PLL), comprising:
- a prediction module, configured to generate a predicted phase error based on a sigma-delta error and to output a phase error correction if the predicted phase error disagrees with an analog early/late signal based on a reference signal and a feedback signal;
- an integer divider, configured to divide by an integer value N a frequency of a phase-corrected multiple of the reference signal that is based on the output of the prediction module and an analog early/late signal;
- and
- a sigma-delta module, configured to change the integer value N in accordance with a non-integer divide ratio.
A method for phase correction, comprising:
- generating a prediction for a phase error based on a sigma-delta error using a processor;
- determining whether the prediction agrees with a determined phase error direction;
- and
- if the prediction does not agree, adjusting a phase correction in accordance with the predicted phase error.
Dependencies are inferred from the claim text.