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公开(公告)号：US11196592B1
公开(公告)日：2021-12-07
申请号：US16937773
申请日：2020-07-24
Applicant: Credo Technology Group Limited
Inventor： Fang Cai , Junqing (Phil) Sun , Haoli Qian
Abstract: Equalization methods and equalizers employing discrete-time filters are provided with dynamic perturbation effect based adaptation. Tap coefficient values may be individually perturbed during the equalization process and the effects on residual ISI monitored to estimate gradient components or rows of a difference matrix. The gradient or difference matrix components may be assembled and filtered to obtain components suitable for calculating tap coefficient updates with reduced adaptation noise. The dynamic perturbation effect based updates may be interpolated with precalculated perturbation effect based updates to enable faster convergence with better accommodation of analog component performance changes attributable to variations in process, supply voltage, and temperature.
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Patent Agency Ranking
公开(公告)号：US11128497B1
公开(公告)日：2021-09-21
申请号：US16920115
申请日：2020-07-02
Applicant: Credo Technology Group Limited
Inventor： Junqing (Phil) Sun , Fang Cai , Tianchen Luo , Haoli Qian
Abstract: Decision feedback equalizers and equalization methods may employ fractional tap unrolling and/or probability-based decision threshold placement. One illustrative fractional tap unrolling equalization method embodiment includes: tracking preceding symbol decisions; converting an equalized signal into tentative symbol decisions with a precompensation unit; and selecting from the tentative symbol decisions based on the preceding symbol decisions. The precompensation unit has a decision element for each combination of a first number of speculative preceding symbols, with comparators in each decision element using a first type of symbol decision threshold that accounts for trailing intersymbol interference from the corresponding combination, and with an additional comparator in at least one of the decision elements using a second type of symbol decision threshold that accounts for trailing intersymbol interference from a second number of speculative preceding symbols, the second number being greater than the first.
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公开(公告)号：US10447509B1
公开(公告)日：2019-10-15
申请号：US16110594
申请日：2018-08-23
Applicant: Credo Technology Group Limited
Inventor： Fang Cai , Junqing Sun , Haoli Qian
Abstract: Precompensator-based quantization techniques offer a way to reduce the complexity and power requirements of clock recovery modules while offering improved timing recovery performance relative to a bang-bang scheme operating in a lossy channel. One illustrative method embodiment includes: (a) obtaining a receive signal having a sequence of symbols from a symbol set, the receive signal exhibiting trailing intersymbol interference; (b) operating on the receive signal with a precompensation unit having a set of comparators to produce, for each sampling instant, a set of comparator results representing a quantized receive signal value, the set of comparators applying a set of threshold values that at least partly compensate for the trailing intersymbol interference; (c) deriving a symbol decision from each set of comparator results; (d) combining the symbol decisions with said quantized receive signal values to determine an estimated timing error for each sampling instant; and (e) filtering the estimated timing errors to generate a sampling clock.
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公开(公告)号：US11424968B1
公开(公告)日：2022-08-23
申请号：US17344323
申请日：2021-06-10
Applicant: Credo Technology Group Limited
Inventor： Junqing Sun , Fang Cai , Hung-Yi Chen , Haoli Qian
Abstract: Disclosed retimer modules and methods enable equalizer training during link speed negotiation. One illustrative retimer module includes: an analog to digital converter that uses a sampling clock to digitize a receive signal; an equalizer that converts the digitized receive signal into an equalized signal; a decision element that derives a receive symbol stream from the equalized signal; and a clock recovery module that derives the sampling clock based at least in part on an equalization error of the equalized signal, the sampling clock having a frequency with a range including a baud rate of the receive signal at a first supported speed and including a frequency not less than twice the baud rate of the receive signal at a second supported speed.
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公开(公告)号：US11570024B2
公开(公告)日：2023-01-31
申请号：US17453066
申请日：2021-11-01
Applicant: CREDO TECHNOLOGY GROUP LIMITED
Inventor： Fang Cai , Junqing (Phil) Sun , Haoli Qian
Abstract: Equalization methods and equalizers employing discrete-time filters are provided with dynamic perturbation effect based adaptation. Tap coefficient values may be individually perturbed during the equalization process and the effects on residual ISI monitored to estimate gradient components or rows of a difference matrix. The gradient or difference matrix components may be assembled and filtered to obtain components suitable for calculating tap coefficient updates with reduced adaptation noise. The dynamic perturbation effect based updates may be interpolated with precalculated perturbation effect based updates to enable faster convergence with better accommodation of analog component performance changes attributable to variations in process, supply voltage, and temperature.
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公开(公告)号：US11231740B2
公开(公告)日：2022-01-25
申请号：US16269491
申请日：2019-02-06
Applicant: CREDO TECHNOLOGY GROUP LIMITED
Inventor： Fang Cai , Junqing Sun , Haoli Qian
Abstract: Disclosed clock recovery modules provide improved performance with only limited complexity and power requirements. In one illustrative embodiment, a clock recovery method includes: oversampling a receive signal to obtain mid-symbol interval (MSI) samples and between-symbol interval (BSI) samples; processing at least the MSI samples to obtain symbol decisions; filtering the symbol decisions to obtain BSI targets; determining a timing error based on a difference between the BSI samples and the BSI targets; and deriving from the timing error a clock signal for said oversampling.
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