Receiver With Tap-Coefficient Adjustments

• US 20130111307A1
• Filed: 10/31/2011
• Published: 05/02/2013
• Est. Priority Date: 10/31/2011
• Status: Active Grant

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Dacheng Zhou
• Inventors: ZHOU, Dacheng, Berkram, Daniel Alan
• Granted Patent: US 8,966,353 B2
• Time in Patent Office: Days
• US Class Current: 714/799
• CPC Class Codes: H04L 2025/0349 as a feedback filter
• CPC Class Codes: H04L 2025/03592 Adaptation methods
• CPC Class Codes: H04L 25/03057 with a recursive structure H04L25/03031 takes precedence

Abstract

A receiver can include a sampler module for sampling a data-bearing input signal to extract data encoded in the data-bearing analog input signal. The sampling results in data-symbol sequences. The data-symbol sequences can be used to identify error events. The identified error events can be used as a basis for adjusting tap coefficients. The tap coefficients can be used in setting reference levels for the sampler module.

Claims

1. A process comprising:

sampling an analog data input signal to yield data-symbol sequences;

identifying sampling events including error events in said data symbol sequences;

adjusting tap coefficients based on said error events; and

setting reference levels for said sampling based in part on said tap coefficients.

2. A process as recited in claim 1 wherein said identifying is based at least in part on comparisons of offset data-symbol sequences.

3. A process as recited in claim 1 wherein said error events include:

adjust-up error events indicating that a reference level is too low, and

adjust-down error events indicating that a reference level is too high.

4. A process as recited in claim 3 wherein said adjusting includes:

accumulating error-event adjustment values associated with said error events to yield accumulated adjustment values for each of said tap coefficients, said error-event adjustment values being accumulated so that values associated with said adjust-down error events offset values associated with said adjust-up error events; and

applying said accumulated adjustment values to respective tap coefficients.

5. A process as recited in claim 1 wherein the reference levels that provide for offset data-symbol sequences are set both above and below a reference level of a sampler providing values for an output data-symbol sequence for a receiver.

6. A process as recited in claim 1 wherein said reference levels for samplers providing offset data-symbol sequences not set both above and below a reference level of a sampler providing values for a receiver-output data-symbol sequence.

7. A process as recited in claim 1 wherein said reference levels for samplers providing offset data-symbol sequences not set both above and below a reference level of a sampler providing values for a reference symbol sequence, but are set either above or below said reference level for said sampler providing values for a receiver-output data-symbol sequence.

8. A process as recited in claim 1 wherein said identifying is based least in part on a comparison of a reference-data symbol sequence and an offset data sequence.

9. A receiver comprising:

a sampler module to generate data-symbol sequences at least in part by sampling an input data signal, said sampler module including samplers for sampling said input data signal relative to reference levels to yield data symbol sequences; and

a decision feedback equalizer to adjust said reference levels based on said data symbol sequences and tap coefficients, said decision feedback equalizer including,

an error-event detector to identify error events based on said data symbol sequences, and

a tap-coefficient adjuster to adjust said tap coefficients based on said error events.

10. A receiver as recited in claim 9 wherein said sampler modules includes:

a first reference data sampler for sampling an input data signal relative to a receiver-output data reference level, and

a first offset data sampler for sampling said input data signal relative to an offset data reference level, said offset data reference level being offsite with respect to said receiver-output data reference level.

11. A receiver as recited in claim 10 wherein error events are detected at least in part by comparing outputs of different samplers of said sampler module.

12. A receiver as recited in claim 11 wherein said different samplers include said first offset sampler and a second offset sampler.

13. A receiver as recited in claim 12 wherein the reference level for said first reference data sampler is maintained between the reference levels for said first offset data sampler and said second offset data sampler.

14. A receiver as recited in claim 11 wherein said different samplers include said first offset data sampler and said first receiver-output data sampler.

15. A receiver as recited in claim 9 wherein each of said tap coefficients corresponds to a different inter-symbol interval size.