System and Method for Adjusting Compensation Applied to a Signal

• US 20070280383A1
• Filed: 05/24/2007
• Published: 12/06/2007
• Est. Priority Date: 05/30/2006
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Hidaka, Yasuo
• Granted Patent: US 7,760,798 B2
• Time in Patent Office: Days
• US Class Current: 375/346
• CPC Class Codes: H04L 2025/03445 Time domain
• CPC Class Codes: H04L 2025/03592 Adaptation methods
• CPC Class Codes: H04L 25/03038 with a non-recursive structure H04L25/03031 takes precedence
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end
• CPC Class Codes: H04L 25/063 Setting decision thresholds using feedback techniques only

Abstract

In one embodiment of the present invention, a method for adjusting a signal includes applying compensation for distortion to a signal to generate an output signal. The method also includes, using a clock signal, sampling the output signal to generate a plurality of data values and boundary values, each value comprising either a high value or a low value based on the sampling of the output signal. The method further includes detecting a transition in value between two successive data values and determining a sampled boundary value between the two successive data values. The method also includes, based only on the high or low values of the boundary value and one or more data values before or after the boundary value, adjusting the compensation applied to the signal.

Claims

1. A method for adjusting a signal, comprising:

applying compensation for distortion to a signal to generate an output signal;

using a clock signal, sampling the output signal to generate a plurality of data values and boundary values, each value comprising either a high value or a low value based on the sampling of the output signal;

detecting a transition in value between two successive data values and determining a sampled boundary value between the two successive data values; and

based only on the high or low values of the boundary value and one or more data values before or after the boundary value, adjusting the compensation applied to the signal.

2. The method of claim 1, wherein the compensation is applied to the signal after the distortion occurs.

3. The method of claim 1, wherein the compensation is applied to the signal before the distortion occurs.

4. The method of claim 3, wherein the compensation is also applied to the signal after the distortion occurs.

5. The method of claim 1, wherein the compensation applied to the signal is adjusted based only on the high or low value of the boundary value and the high or low value of the data value arriving immediately before the two successive data values.

6. The method of claim 5, wherein the boundary value and the data value arriving immediately before the two successive data values are compared using an inverted correlation function.

7. The method of claim 5, wherein the boundary value and the data value arriving immediately before the two successive data values are compared using a correlation function.

8. The method of claim 5, wherein the boundary value and the data value arriving immediately before the two successive data values are compared using an exclusive-OR operation.

9. The method of claim 5, wherein the boundary value and the data value arriving immediately before the two successive data values are compared using an exclusive-NOR operation.

10. The method of claim 5, wherein the compensation applied to the signal is increased when the boundary value and the data value arriving immediately before the successive data values comprise the same high or low value.

11. The method of claim 5, wherein the compensation applied to the signal is decreased when the boundary value and the data value arriving immediately before the successive data values do not comprise the same high or low value.

12. The method of claim 1, wherein the compensation applied to the signal is adjusted based only on the high or low value of the boundary value and the high or low value of the data value 1.5 symbols before the boundary value.

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

14. The method of claim 1, wherein no transition in value necessarily occurs immediately before the two successive data values.

15. The method of claim 1, wherein the transition in value is detected and the compensation is adjusted by:

identifying a filter pattern of a plurality of pre-determined filter patterns that corresponds to the plurality of sampled data values and boundary values, each pre-determined filter pattern being associated with a particular adjustment of the compensation applied to the signal; and

adjusting the compensation based on the particular adjustment of the compensation associated with the identified filter pattern.

16. An adaptive equalizer, comprising:

an equalizer configured to apply compensation for distortion to a signal to generate an output signal;

a sampler configured to;

receive the output signal and a clock signal; and

using the clock signal, sample the output signal to generate a plurality of data values and boundary values, each value comprising either a high value or a low value based on the sampling of the output signal; and

a controller configured to;

detect a transition in value between two successive data values and determine a sampled boundary value between the two successive data values; and

adjust the compensation applied by the equalizer to the signal based only on the high or low values of the boundary value and one or more data values before or after the boundary value.

17. The adaptive equalizer of claim 16, wherein the compensation is applied to the signal after the distortion occurs.

18. The adaptive equalizer of claim 16, wherein the compensation is applied to the signal before the distortion occurs.

19. The adaptive equalizer of claim 18, wherein the compensation is also applied to the signal after the distortion occurs.

20. The adaptive equalizer of claim 16, wherein the compensation applied to the signal is adjusted based only on the high or low value of the boundary value and the high or low value of the data value arriving immediately before the two successive data values.

21. The adaptive equalizer of claim 20, wherein the boundary value and the data value arriving immediately before the two successive data values are compared using an inverted correlation function.

22. The adaptive equalizer of claim 20, wherein the boundary value and the data value arriving immediately before the two successive data values are compared using a correlation function.

23. The adaptive equalizer of claim 20, wherein the boundary value and the data value arriving immediately before the two successive data values are compared using an exclusive-OR operation.

24. The adaptive equalizer of claim 20, wherein the boundary value and the data value arriving immediately before the two successive data values are compared using an exclusive-NOR operation.

25. The adaptive equalizer of claim 20, wherein the compensation applied to the signal is increased when the boundary value and the data value arriving immediately before the successive data values comprise the same high or low value.

26. The adaptive equalizer of claim 20, wherein the compensation applied to the signal is decreased when the boundary value and the data value arriving immediately before the successive data values do not comprise the same high or low value.

27. The adaptive equalizer of claim 16, wherein the compensation applied to the signal is adjusted based only on the high or low value of the boundary value and the high or low value of the data value 1.5 symbols before the boundary value.

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

29. The adaptive equalizer of claim 16, wherein no transition in value necessarily occurs immediately before the two successive data values.

30. The adaptive equalizer of claim 16, wherein the transition in value is detected and the compensation is adjusted by:

identifying a filter pattern of a plurality of pre-determined filter patterns that corresponds to the plurality of sampled data values and boundary values, each pre-determined filter pattern being associated with a particular adjustment of the compensation applied to the signal; and

adjusting the compensation based on the particular adjustment of the compensation associated with the identified filter pattern.