High-speed signaling systems and methods with adaptable, continuous-time equalization

1. An integrated circuit to receive a series of symbols over a communication channel, the integrated circuit comprising:

a continuous-time equalizer to reduce intersymbol interference from a most-recently received symbol in the series;

a decision-feedback equalizer to reduce intersymbol interference from symbols other than the most-recently received symbol in the series;

a data sampler to produce data samples from an equalized signal generated by the continuous-time equalizer and the decision-feedback equalizer; and

an adaptation engine to separately adjust a a low-frequency gain and a high-frequency gain provided by the continuous-time equalizer in dependence on the most-recently received symbol in the series, the adaptation engine to adjust an amount of equalization provided by the decision-feedback equalizer in dependence on the symbols other than the most-recently received symbol in the series and independent of the most-recently received symbol in the series.

2. The integrated circuit of claim 1 , the adaptation engine to adjust the low-frequency gain and the high-frequency gain in dependence on the most-recently received symbol in the series and a current symbol in the series.

3. The integrated circuit of claim 1 , where:

the continuous-time equalizer is to reduce the intersymbol interference associated only with the most-recently received symbol in the series and the decision-feedback equalizer is to reduce the intersymbol interference only from symbols other than the most-recently received symbol in the series.

4. The integrated circuit of claim 3 , the adaptation engine to adjust the low-frequency gain responsive to a comparison between an error sample and one of the data samples.

5. The integrated circuit of claim 1 , where the adaptation engine adjusts the low-frequency gain relative to the high-frequency gain in dependence on the most-recently received symbol.

6. An integrated circuit to receive a series of symbols over a communication channel, the integrated circuit comprising:

a continuous-time equalizer to reduce intersymbol interference from a most-recently received symbol in the series;

a decision-feedback equalizer to reduce intersymbol interference from symbols other than the most-recently received symbol in the series;

a data sampler to produce data samples from an equalized signal generated by the continuous-time equalizer and the decision-feedback equalizer;

an adaptation engine to generate a first control value to adjust a low-frequency gain provided by the continuous-time equalizer and at least a second control value to adjust a high-frequency gain provided by the continuous-time equalizer, the first or the second control values being controlled so as to reduce intersymbol interference from the most-recently received symbol in the series; and

a second sampler to generate error samples representing divergence of the equalized signal from an expected data-carrying level of the equalized signal;

the adaptation engine to generate the first control value responsive to the error samples.

7. An integrated circuit to receive a series of symbols over a communication channel, the integrated circuit comprising:

a continuous-time equalizer to reduce intersymbol interference from a most-recently received symbol in the series;

a decision-feedback equalizer to reduce intersymbol interference from symbols other than the most-recently received symbol in the series;

a data sampler to produce data samples from an equalized signal generated by the continuous-time equalizer and the decision-feedback equalizer;

a second sampler to generate error samples representing divergence of the equalized signal from an expected data-carrying level of the equalized signal;

an adaptation engine responsive to the error samples to control the continuous-time equalizer to urge a data-carrying level of the equalized signal for a current symbol toward the expected data-carrying level; and

a data filter to enable change in control of the continuous-time equalizer only when incoming symbols match predetermined values.

8. A method for sampling a series of symbols over a communication channel, the series of symbols including an incoming symbol and a most-recently-received symbol immediately preceding the incoming symbol, the method comprising:

applying continuous-time equalization to the series of symbols to produce a first equalized signal;

applying decision-feedback equalization to the first equalized signal to produce a second equalized signal;

sampling the second equalized signal to produce a series of data samples, including an incoming sample of the incoming symbol and a most-recently-received sample of the most-recently-received symbol;

where the applying continuous-time equalization includes reducing intersymbol interference from the most-recently-received symbol, and where applying decision feedback equalization includes using one or more taps to produce the second equalized signal in a manner in which none of the one or more taps is dependent upon the most-recently-received sample for the most-recently-received symbol; and

controlling low-frequency gain of the continuous-time equalization relative to high-frequency gain of the continuous-time equalization and responsively adjusting continuous-time equalization so as to reduce the intersymbol interference from the most-recently-received prior symbol, and adjusting decision-feedback equalization so as to reduce intersymbol interference in the first equalized signal not attributable to the most-recently-received symbol;

where the applying continuous-time equalization further includes providing a first gain for low frequencies and a second gain for high frequencies, and both decreasing the low frequency gain and increasing the high frequency gain if a current error sample has the same logic value as a data value of an immediately preceding symbol.

9. The method of claim 8 , where controlling the low-frequency gain of the continuous-time equalization includes adjusting the low-frequency gain of the continuous-time equalization in dependence upon an expected data-carrying level of the incoming signal.

10. The method of claim 8 , further comprising generating error samples representing differences between expected data-carrying levels and equalized-signal levels, and adjusting the continuous-time equalization responsive to the error samples.

11. The integrated circuit of claim 1 , the adaptation engine to adjust at least one of the low-frequency gain or the high-frequency gain in dependence on the most-recently received symbol in the series and a current symbol in the series.

12. The integrated circuit of claim 1 , where the adaptation engine adjusts both the low-frequency gain and the high-frequency gain in dependence on the most-recently received symbol.

13. The integrated circuit of claim 12 , wherein the adaptation engine adjusts both the low-frequency gain and the high-frequency gain in dependence on an error sample.

14. The integrated circuit of claim 1 , further comprising an error sampler to produce error samples, the adaptation engine to adjust the low-frequency gain and the high-frequency gain responsive comparisons between the error samples and the data samples.