System and method for independently adjusting multiple offset compensations applied to a signal

• US 7,817,757 B2
• Filed: 05/24/2007
• Issued: 10/19/2010
• Est. Priority Date: 05/30/2006
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Hidaka, Yasuo
• Primary Examiner(s): Ahn; Sam K
• Application Number:
  US11/753,116
• Publication Number:
  US 20070280384A1
• Time in Patent Office: 1,244 Days
• Field of Search: 375229-236, 333/18, 333/28.R, 708/300, 708/322, 708/323, 379/340, 379/398
• US Class Current: 375/350
• CPC Class Codes: H04L 25/03885 adaptive
• 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 receiving an input data signal and communicating a first portion of the input data signal on a first path and a second portion of the input data signal on a second path. The method also includes applying a first offset compensation to the first path and a second offset compensation to the second path. The method further includes combining at least the first path and the second path 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 at least on the high or low value of the boundary value and on the high or low value of at least two data values arriving immediately before the boundary value, independently adjusting the first offset compensation applied to the first path and the second offset compensation applied to the second path.

Claims

1. A method for adjusting a signal, comprising:

receiving an input data signal at an input port;

using a divider, communicating a first portion of the input data signal on a first path and a second portion of the input data signal on a second path, wherein the first path is an unmodified input data signal path and the second path is a first-order derivative input data signal path;

applying a first offset compensation to the first path using a first amplifier and a second offset compensation to the second path using a second amplifier;

combining at least the first path and the second path using a mixer to generate an output signal;

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

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

based at least on the high or low value of the boundary value and on the high or low value of at least two data values arriving immediately before the boundary value, independently adjusting using the controller the first offset compensation applied to the first path and the second offset compensation applied to the second path.

2. The method of claim 1, wherein the first offset compensation applied to the first path and the second offset compensation applied to the second path are independently adjusted based at least on the high or low value of the boundary value and on the high or low value of at least the data values 0.5 and 1.5 symbols before the boundary value.

3. The method of claim 1, wherein at least one of the first offset compensation and second offset compensation is made positive when the boundary value is low.

4. The method of claim 1, wherein at least one of the first offset compensation and second offset compensation is made negative when the boundary value is high.

5. The method of claim 1, wherein at least the first offset compensation applied to the unmodified input data signal path is adjusted if the high or low values of the two data values arriving immediately before the boundary value are different.

6. The method of claim 1, wherein at least the second offset compensation applied to the first-order derivative input data signal path is adjusted if the high or low values of the two data values arriving immediately before the boundary value are the same.

7. The method of claim 1, further comprising:

further communicating a third portion of the input data signal on a third path, the third path comprising a second-order derivative input data signal path;

further applying a third offset compensation to the third path;

combining the first path, the second path, and the third path to generate an output signal; and

based at least on the high or low value of the boundary value and on the high or low value of at least three data values arriving immediately before the boundary value, independently adjusting the first offset compensation applied to the first path, the second offset compensation applied to the second path, and the third offset compensation applied to the third path.

8. The method of claim 7, wherein at least the third offset compensation applied to the second-order derivative input data signal path is adjusted if the high or low values of the three data values arriving immediately before the boundary value are the same.

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

10. The method of claim 1, wherein the input data signal is not a test signal.

11. A receiver, comprising:

an input port configured to receive an input data signal;

a divider configured to communicate a first portion of the input data signal on a first path and a second portion of the input data signal on a second path, wherein the first path is an unmodified input data signal path and the second path is a first-order derivative input data signal path;

a first amplifier configured to apply a first offset compensation to the first path;

a second amplifier configured to apply a second offset compensation to the second path;

a mixer configured to combine at least the first path and the second path 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 data value and boundary value comprising either a high value or a low value based on the sampling of the output signal; and

an adaptive 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

based at least on the high or low value of the boundary value and on the high or low value of at least two data values arriving immediately before the boundary value, independently adjust the first offset compensation applied to the first path and the second offset compensation applied to the second path.

12. The receiver of claim 11, wherein the first offset compensation applied to the first path and the second offset compensation applied to the second path are independently adjusted based at least on the high or low value of the boundary value and on the high or low value of at least the data values 0.5 and 1.5 symbols before the boundary value.

13. The receiver of claim 11, wherein at least one of the first offset compensation and second offset compensation is made positive when the boundary value is low.

14. The receiver of claim 11, wherein at least one of the first offset compensation and second offset compensation is made negative when the boundary value is high.

15. The receiver of claim 11, wherein at least the first offset compensation applied to the unmodified input data signal path is adjusted if the high or low values of the two data values arriving immediately before the boundary value are different.

16. The receiver of claim 11, wherein at least the second offset compensation applied to the first-order derivative input data signal path is adjusted if the high or low values of the two data values arriving immediately before the boundary value are the same.

17. The receiver of claim 11, wherein the divider is further configured to communicate a third portion of the input data signal on a third path, the third path comprising a second-order derivative input data signal path;

the receiver further comprising a third amplifier configured to apply a third offset compensation to the third path;

wherein;

the mixer is further configured to combine the first path, the second path, and the third path to generate an output signal; and

the adaptive controller is further configured to, based at least on the high or low value of the boundary value and on the high or low value of at least three data values arriving immediately before the boundary value, independently adjust the first offset compensation applied to the first path, the second offset compensation applied to the second path, and the third offset compensation applied to the third path.

18. The receiver of claim 17, wherein at least the third offset compensation applied to the second-order derivative input data signal path is adjusted if the high or low values of the three data values arriving immediately before the boundary value are the same.

19. The receiver of claim 11, wherein the clock signal is associated with the output signal.

20. The receiver of claim 11, wherein the input data signal is not a test signal.