Equalization in high speed links through in-situ channel estimation

A system for estimating performance of a serial communication channel configured to transmit a binary input stream from a transmitter to an output stream at a receiver, the receiver comprising:

• a non-volatile storage medium;
• and
• a processor configured to:
• model the channel as a finite impulse response (FIR) filter model, the modeling comprising:
• estimating a cursor pulse response of the FIR filter model by analyzing the output stream received at the receiver;
• estimating one or more pre-cursor or post-cursor pulse responses of the FIR filter model from the received output stream using the estimated cursor pulse response;
• and
• storing the estimated cursor, pre-cursor, and post-cursor pulse responses on the non-volatile storage medium;
• determine a performance metric by using the estimated one or more pre-cursor or post-cursor pulse responses;
• and
• store the performance metric on the non-volatile storage medium,
• wherein:
• the performance metric consist of:
• a pre-cursor pulse response;
• or
• a post-cursor pulse response, or
• the determining of the performance metric comprises evaluating an expression selected from the group consisting of:
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• wherein h0 is the estimated cursor pulse response, hi, for i<0, is the ith estimated pre-cursor pulse response, hi, for i>0, is the ith estimated post-cursor pulse response, and, when the receiver comprises a decision feedback equalizer, numDFEtaps is a number of taps of the decision feedback equalizer.

A method for tuning a continuous time linear equalizer (CTLE) in a receiver of a serial communication channel using a processor, the channel being configured to transmit a binary input stream from a transmitter to an output stream at the receiver, the CTLE being configured to be tuned by selecting one of a plurality of settings including a default setting, the method comprising:

• modeling by the processor the channel after the CTLE as a finite impulse response (FIR) filter model, the modeling comprising:
• estimating a cursor pulse response of the FIR filter model by analyzing the output stream received at the receiver using the default setting;
• and
• estimating one or more pre-cursor or post-cursor pulse responses of the FIR filter model from the received output stream using the estimated cursor pulse response;
• determining by the processor a performance metric by using the estimated one or more pre-cursor or post-cursor pulse responses;
• repeating the estimating of the one or more pre-cursor or post-cursor pulse responses and the determining of the performance metric for more of the settings;
• comparing by the processor the performance metric for one of the settings to the performance metric for another one of the settings;
• and
• tuning by the processor the CTLE by selecting one of the settings based on the comparison,
• wherein:
• the performance metric consist of:
• a pre-cursor pulse response;
• or
• a post-cursor pulse response, or
• the determining of the performance metric comprises evaluating an expression selected from the group consisting of:
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• wherein h0 is the estimated cursor pulse response, hi, for i<0, is the ith estimated pre-cursor pulse response, hi, for i>0, is the ith estimated post-cursor pulse response, and, when the receiver comprises a decision feedback equalizer, numDFEtaps is a number of taps of the decision feedback equalizer.