System and method for adjusting compensation applied to a signal using filter patterns

• US 7,801,208 B2
• Filed: 05/24/2007
• Issued: 09/21/2010
• Est. Priority Date: 05/30/2006
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Hidaka, Yasuo
• Primary Examiner(s): Ahn; Sam K
• Application Number:
  US11/753,042
• Publication Number:
  US 20070297248A1
• Time in Patent Office: 1,216 Days
• Field of Search: 375229-236, 333/18, 333/28.R, 708/300, 708/322, 708/323, 379/340, 379/398
• US Class Current: 375/229
• CPC Class Codes: H04L 25/03885 adaptive
• CPC Class Codes: H04L 25/063 Setting decision thresholds using feedback techniques only
• CPC Class Codes: H04L 7/0087 Preprocessing of received signal for synchronisation, e.g. by code conversion, pulse generation or edge detection

Abstract

A method for adjusting a signal includes applying compensation to a data signal to generate an output signal and sampling the output signal to generate data values and an error value, each data value comprising either a high value or a low value based on the sampling of the output signal, the error value indicating residue of the distortion based on the sampling of the output signal. The method further includes monitoring the output signal for a pattern of data values corresponding to one or more filter patterns, the filter patterns each comprising a pattern of data values pre-determined to occur substantially equally in data beginning with even data and in data beginning with odd data. The method also includes detecting a pattern of data values in the output signal matching one of the filter patterns and adjusting the compensation applied to the data signal based on the error value.

Claims

1. A method for adjusting a signal, comprising:

applying at least one of a loss compensation for frequency-dependent distortion and an offset compensation for direct current (DC)-offset distortion to a data signal using an equalizer before or after the distortion occurs to generate an output signal, the data signal comprising even data and odd data;

using a clock signal, sampling the output signal at a sampler to generate a plurality of data values and an error value, each data value comprising either a high value or a low value based on the sampling of the output signal, the error value indicating residue of the distortion based on the sampling of the output signal;

monitoring the output signal using a controller for a pattern of data values corresponding to one or more filter patterns, the filter patterns each comprising a pattern of data values pre-determined to occur substantially equally in the data beginning with even data and in the data beginning with odd data of the data signal;

detecting a pattern of data values in the output signal matching one of the filter patterns using the controller; and

using the controller, adjusting at least one of the loss compensation and the offset compensation applied to the data signal based on the error value.

2. The method of claim 1, wherein the error value comprises either a high value or a low value.

3. The method of claim 1, wherein:

the error value comprises at least one boundary value sampled at a transition in value between two successive data values; and

each filter pattern includes a transition in value between the corresponding two successive data values.

4. The method of claim 1, wherein the adjustment of compensation applied to the data signal is further based on the high or low values of one or more data values in the detected pattern of data values.

5. The method of claim 4, wherein the adjustment of the loss compensation applied to the data signal is further based on a Zero-Forcing algorithm using the error value and the high or low values of one or more data values in the detected pattern of data values.

6. The method of claim 4, wherein the adjustment of the loss compensation applied to the data signal is further based on a Least-Mean-Square algorithm using the error value and the high or low values of one or more data values in the detected pattern of data values.

7. The method of claim 2, wherein the adjustment of the loss compensation applied to the data signal is further based on a Sign-Sign-Least-Mean-Square algorithm using the high or low error value and the high or low values of one or more data values in the detected pattern of data values.

8. The method of claim 1, wherein:

the error value comprises a pulse-width value;

the pulse-width value is derived from two successive boundary values and an in-between data value in three successive data values comprising two transitions; and

the loss compensation applied to the data signal is based on the pulse-width value.

9. The method of claim 1, wherein the data signal comprises a quasi-periodic or periodic signal.

10. The method of claim 1, wherein the data signal comprises at least one of a random sequence, at least a portion of an 8B10B idle data sequence, and at least a portion of an 8B10B CJPAT data sequence.

11. The method of claim 1, wherein the filter patterns each comprise at least five data values.

12. The method of claim 3, wherein the transition corresponding to the at least one boundary value is between the last two data values of the detected pattern of data values.

13. The method of claim 12, wherein the loss compensation applied to the data signal is adjusted based only on the boundary value and the data value arriving 1.5 symbols before the boundary value.

14. The method of claim 1, wherein the clock signal is associated with the output signal.

15. The method of claim 1, wherein:

a first portion of the data signal is communicated on a first path and a second portion of the data signal is communicated on a second path; and

the at least one of the loss compensation and the offset compensation is applied to the first path;

the method further comprising;

applying at least one of a loss compensation and an offset compensation to the second path;

combining at least the first path and the second path to apply compensation to the data signal to generate the output signal; and

independently adjusting at least one of the loss compensation and/or the offset compensation applied to the first path and the loss compensation and/or the offset compensation applied to the second path based on the error value and the high or low values of the one or more data values in the detected pattern of data values.

16. An adaptive equalizer, comprising:

an equalizer configured to apply at least one of a loss compensation for frequency-dependent distortion and an offset compensation for direct current (DC)-offset distortion to a data signal before or after the distortion occurs to generate an output signal, the data signal comprising even data and odd data,;

a sampler configured to, using a clock signal, sample the output signal to generate a plurality of data values and an error value, each data value comprising either a high value or a low value based on the sampling of the output signal, the error value indicating residue of the distortion based on the sampling of the output signal; and

a controller configured to;

monitor the output signal for a pattern of data values corresponding to one or more filter patterns, the filter patterns each comprising a pattern of data values pre-determined to occur substantially equally in the data beginning with even data and in the data beginning with odd data of the data signal;

detect a pattern of data values in the output signal matching one of the filter patterns; and

adjust at least one of the loss compensation and the offset compensation applied to the data signal based on the error value.

17. The adaptive equalizer of claim 16, wherein the error value comprises either a high value or a low value.

18. The adaptive equalizer of claim 16, wherein:

the error value comprises at least one boundary value sampled at a transition in value between two successive data values; and

each filter pattern includes a transition in value between the corresponding two successive data values.

19. The adaptive equalizer of claim 16, wherein the controller is configured to adjust the compensation applied to the data signal further based on the high or low value of one or more data values in the detected pattern of data values.

20. The adaptive equalizer of claim 19, wherein the controller is configured to adjust the loss compensation applied to the data signal further based on a Zero-Forcing algorithm using the error value and the high or low values of one or more data values in the detected pattern of data values.

21. The adaptive equalizer of claim 19, wherein the controller is configured to adjust the loss compensation applied to the data signal further based on a Least-Mean-Square algorithm using the error value and the high or low values of one or more data values in the detected pattern of data values.

22. The adaptive equalizer of claim 17, wherein the controller is configured to adjust the loss compensation applied to the data signal further based on a Sign-Sign-Least-Mean-Square algorithm using the high or low error value and the high or low values of one or more data values in the detected pattern of data values.

23. The adaptive equalizer of claim 16, wherein:

the error value comprises a pulse-width value;

the pulse-width value is derived from two successive boundary values and an in-between data value in three successive data values comprising two transitions; and

the loss compensation applied to the data signal is based on the pulse-width value.

24. The adaptive equalizer of claim 16, wherein the data signal comprises a quasi-periodic or periodic signal.

25. The adaptive equalizer of claim 16, wherein the data signal comprises at least one of a random sequence, at least a portion of an 8B10B idle data sequence, and at least a portion of an 8B10B CJPAT data sequence.

26. The adaptive equalizer of claim 16, wherein the filter patterns each comprise at least five data values.

27. The adaptive equalizer of claim 18, wherein the transition corresponding to the at least one boundary value is between the last two data values of the detected pattern of data values.

28. The adaptive equalizer of claim 27, wherein the loss compensation applied to the data signal is adjusted based only on the boundary value and the data value arriving 1.5 symbols before the boundary value.

29. The adaptive equalizer of claim 16, wherein the clock signal is associated with the output signal.

30. The adaptive equalizer of claim 16, wherein the equalizer comprises:

a divider configured to communicate a first portion of the data signal on a first path and a second portion of the data signal on a second path;

a first one of an amplifier or a tap configured to apply the at least one of the loss compensation and the offset compensation to the first path;

a second one of an amplifier or a tap configured to apply at least one of a loss compensation and an offset compensation to the second path; and

a mixer configured to combine at least the first path and the second path to apply compensation to the data signal to generate the output signal, wherein the controller is further configured to independently adjust at least one of the loss compensation and/or the offset compensation applied to the first path and the loss compensation and/or the offset compensation applied to the second path based on the error value and the high or low values of the one or more data values in the detected pattern of data values.