System and method for the non-linear adjustment of compensation applied to a signal

• US 7,839,955 B2
• Filed: 05/24/2007
• Issued: 11/23/2010
• 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:
  US11/753,060
• Publication Number:
  US 20070280390A1
• Time in Patent Office: 1,279 Days
• Field of Search: 375229-236, 333/18, 333/28.R, 708/300, 708/322, 708/323, 379/340, 379/398
• US Class Current: 375/316
• CPC Class Codes: G01D 21/00 Measuring or testing not otherwise provided for
• 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 loss compensation for frequency-dependent distortion to a signal before or after the distortion occurs 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, based only on the high or low values of one or more of the data values and boundary values, adjusting the loss compensation applied to the signal, where if the loss compensation applied to the signal is to be increased, the loss compensation is increased by a first amount, if the loss compensation applied to the signal is to be decreased, the loss compensation is decreased by a second amount, the magnitude of the first amount is not equal to the magnitude of the second amount, the first amount and the second amount are associated with a control target value, and the control target value is adjusted dynamically based on the value of the loss compensation applied to the signal.

Claims

1. A method for adjusting a signal, comprising:

using an equalizer, applying loss compensation for frequency-dependent distortion to a signal before or after the distortion occurs 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; and

based only on the high or low values of one or more of the data values and boundary values, adjusting the loss compensation applied to the signal using a controller, wherein;

if the loss compensation applied to the signal is to be increased, the loss compensation is increased by a first amount;

if the loss compensation applied to the signal is to be decreased, the loss compensation is decreased by a second amount;

the magnitude of the first amount is not equal to the magnitude of the second amount;

the first amount and the second amount are associated with a control target value; and

the control target value is adjusted dynamically based on the value of the loss compensation applied to the signal.

2. The method of claim 1, further comprising detecting a transition in value between two successive data values and determining a sampled boundary value between the two successive data values, wherein the loss compensation applied to the signal is adjusted based only on the high or low values of the sampled boundary value between the two successive data values and one or more data values before or after the boundary value.

3. The method of claim 2, wherein the loss 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.

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

5. The method of claim 1, wherein the control target value is adjusted to vary directly with the value of the loss compensation applied.

6. The method of claim 1, wherein the control target value is adjusted to vary within a fixed range.

7. The method of claim 6, wherein the fixed range is approximately between −

0.6 and +0.5.

8. An adaptive equalizer, comprising:

an equalizer configured to apply loss compensation for frequency-dependent distortion to a signal before or after the distortion occurs 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

a controller configured to adjust the loss compensation applied to the input data signal based only on the high or low value of one or more of the data values and boundary values, wherein;

if the loss compensation applied to the signal is to be increased, the loss compensation is increased by a first amount;

if the loss compensation applied to the signal is to be decreased, the loss compensation is decreased by a second amount;

the magnitude of the first amount is not equal to the magnitude of the second amount;

the first amount and the second amount are associated with a control target value; and

the control target value is adjusted dynamically based on the value of the loss compensation applied to the signal.

9. The adaptive equalizer of claim 8, wherein the controller is further configured to detect a transition in value between two successive data values and determine a sampled boundary value between the two successive data values, wherein the loss compensation applied to the signal is adjusted based only on the high or low values of the sampled boundary value between the two successive data values and one or more data values before or after the boundary value.

10. The adaptive equalizer of claim 9, wherein the loss 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.

11. The adaptive equalizer of claim 8, wherein the clock signal is associated with the output signal.

12. The adaptive equalizer of claim 8, wherein the control target value is adjusted to vary directly with the value of the loss compensation applied.

13. The adaptive equalizer of claim 8, wherein the control target value is adjusted to vary within a fixed range.

14. The adaptive equalizer of claim 13, wherein the fixed range is approximately between −

0.6 and +0.5.