Phase alignment circuitry and methods
First Claim
1. A method of detecting phase of transitions in a data signal relative to a reference clock signal comprising:
- producing a plurality of phase-shifted versions of the reference clock signal;
using each of the plurality of phase-shifted versions of the reference clock signal in order of magnitude of phase shift to sample the data signal and thereby produce samples of the data signal;
comparing the samples to a training pattern that is initially aligned with training data in the data signal;
re-aligning the training pattern with the training data each time use of one of the plurality of phase-shifted versions of the reference clock signal causes the training pattern to become misaligned with the training data; and
analyzing information including which of the plurality of phase-shifted versions of the reference clock signal caused misalignment to approximate the phase of the transitions.
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Accused Products
Abstract
The phase of a data signal relative to a reference clock signal is approximated relatively accurately using only relatively coarse increments of phase shift between trial version of a sampling clock signal (derived from the reference clock signal). Information about which amounts of progressively greater phase shift in the sampling clock signal cause loss of alignment between a training pattern and training data in the data signal can be used for such purposes as identifying the amount of phase of shift of the reference clock signal that will be best for use in sampling the data signal during normal (post-training) operation.
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Citations
21 Claims
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1. A method of detecting phase of transitions in a data signal relative to a reference clock signal comprising:
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producing a plurality of phase-shifted versions of the reference clock signal; using each of the plurality of phase-shifted versions of the reference clock signal in order of magnitude of phase shift to sample the data signal and thereby produce samples of the data signal; comparing the samples to a training pattern that is initially aligned with training data in the data signal; re-aligning the training pattern with the training data each time use of one of the plurality of phase-shifted versions of the reference clock signal causes the training pattern to become misaligned with the training data; and analyzing information including which of the plurality of phase-shifted versions of the reference clock signal caused misalignment to approximate the phase of the transitions. - View Dependent Claims (2, 3, 4, 5, 6)
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7. Apparatus for detecting phase of transitions in a data signal relative to a reference clock signal comprising:
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a plurality of delay circuit elements for producing a plurality of phase-shifted versions of the reference clock signal; selection circuitry for selectively selecting each of the plurality of phase-shifted versions of the reference clock signal in order of magnitude of phase shift as a sampling clock signal for sampling the data signal; comparison circuitry for comparing samples of the data signal, taken using the sampling clock signal, to a training pattern; alignment circuitry for initially aligning the training pattern with training data in the data signal and for subsequently re-aligning the training pattern with the training data each time use of one of the plurality of phase-shifted versions of the reference clock signal causes the training pattern to become misaligned with the training data; and circuitry for monitoring which of the plurality of phase-shifted versions of the reference clock signal caused misalignment of the training pattern with the training data. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. Apparatus for detecting phase of transitions in a data signal relative to a reference clock signal comprising:
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a plurality of delay circuit elements for producing a plurality of phase-shifted versions of the reference clock signal; selection circuitry for selectively selecting each of the phase-shifted versions of the reference clock signal in order of magnitude of phase shift as a sampling clock signal for sampling the data signal; comparison circuitry for comparing samples of the data signal, taken using the sampling clock signal, to a training pattern; alignment circuitry for initially aligning the training pattern with training data in the data signal and for subsequently re-aligning the training pattern with the training data each time use of one of the phase-shifted versions of the reference clock signal causes the training pattern to become misaligned with the training data; and circuitry for monitoring which of the phase-shifted versions of the reference clock signal caused misalignment of the training pattern with the training data, wherein the selection circuitry includes means for advancing to a next one of the phase-shifted versions of the reference clock signal after the comparison circuitry detects an instance of data corresponding to the training pattern in the data signal or a non-correspondence between the data signal and the training pattern.
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20. Apparatus for detecting phase of transitions in a data signal relative to a reference clock signal comprising:
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a plurality of delay circuit elements for producing a plurality of phase-shifted versions of the reference clock signal; selection circuitry for selectively selecting each of the phase-shifted versions of the reference clock signal in order of magnitude of phase shift as a sampling clock signal for sampling the data signal; comparison circuitry for comparing samples of the data signal, taken using the sampling clock signal, to a training pattern; alignment circuitry for initially aligning the training pattern with training data in the data signal and for subsequently re-aligning the training pattern with the training data each time use of one of the phase-shifted versions of the reference clock signal causes the training pattern to become misaligned with the training data; and circuitry for monitoring which of the phase-shifted versions of the reference clock signal caused misalignment of the training pattern with the training data, wherein the alignment circuitry comprises; means for selectively recirculating the training pattern in synchronism with the sampling clock signal and wherein the means for selectively recirculating comprises; means for halting the recirculating during initial aligning and subsequent re-aligning of the training pattern with the training data.
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21. A method of determining an amount of phase shift of a reference clock signal that will render that signal advantageous for use in sampling a data signal that may be skewed relative to the reference clock signal comprising:
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aligning a training pattern with training data in the data signal; using a sampling clock signal based on the reference clock signal to sample the data signal and advance the training pattern; comparing the advancing training pattern to the data signal samples until the training pattern is complete or until a lack of correspondence between the training pattern and a data signal sample is detected; shifting the phase of the sampling clock signal by a predetermined amount after completion of the comparing; re-aligning the training pattern with the training data if the comparing is completed by detection of a lack of correspondence; repeating the using, comparing, shifting, and re-aligning until the total amount of phase shift due to the shifting is at least greater than the duration of any two successive bits in the data signal; and sampling the data signal subsequent to the training data with a phase that is determined based at least in part on information as to which iterations of the comparing were completed by detection of a lack of correspondence.
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Specification