Adaptive cascaded equalization circuits with configurable roll-up frequency response for spectrum compensation

Patent metadata

Field	Value
Publication number	US-9917707-B2
Application number	US-201514848875-A
Country	US
Kind code	B2
Filing date	Sep 9, 2015
Priority date	Sep 11, 2014
Publication date	Mar 13, 2018
Grant date	Mar 13, 2018

Abstract

The present disclosure provides adaptive cascaded equalization circuits for frequency spectrum compensation. The cascaded equalization are formed in circuit configurations to achieve configurable roll-up frequency responses to compensate for the loss of signal channels in the wire-line or optical communications, particularly but not exclusively, for the loss of signal trace in the wire-line communications, and photodetectors used in the optical communications. These cascaded equalization circuits include two or more stages of equalizers. The peaking frequencies of each stage are set to be different from each other, so that the overall frequency response characteristic has a unique frequency response with a roll-up slope. The equalization function is automatically tuned by an adaptive feedback control loop.

First claim

The invention claimed is:

1. A device for reducing channel loss in high data rate transmission, the device comprising:
at least two equalizers connected in series;
at least one gain stage interspersed between two consecutive equalizers of the at least two equalizers, the at least one gain stage being configured to compensate for gain loss between equalization stages corresponding to the at least two equalizers; and
an adaptive feedback circuit, configured to provide an adaptive feedback control loop which automatically tunes an equalization function associated with the at least two equalizers and the at least one gain stage, wherein one end of the adaptive circuit is connected to an output of the at least two equalizers and the other end is connected to a control input that adjusts each of the at least two equalizers;
wherein automatically tuning the equalization function includes setting the peaking frequencies of each equalization stage to be different from one another, and an overall frequency response of the equalization function has a roll-up characteristic configured to compensate for channel loss.

2. The device according to claim 1 , wherein each of the at least two equalizers is independently enabled and disabled.

3. The device according to claim 1 , wherein the adaptive feedback circuit determines a control signal to the control input by comparing a high-frequency signal output of the at least two equalizer with a low-frequency signal output of the at least two equalizers.

4. The device according to claim 1 , wherein the adaptive feedback circuit comprises a low pass filter and a differential power detector, the differential power detector being configured to compare the output of the at least two equalizers with an output of the low pass filter, and the low pass filter being configured to filter the output of the at least two equalizers.

5. A high speed data transmission system comprising:
a lossy channel;
at least two equalizers; at least one gain stage interspersed between two consecutive equalizers of the at least two equalizers, the at least one gain stage being configured to compensate for gain loss between equalization stages corresponding to the equalizers; and
an adaptive feedback circuit, configured to provide an adaptive feedback control loop which automatically tunes an equalization function associated with the at least two equalizers and the at least one gain stage, wherein one end of the adaptive circuit is connected to an output of the at least two equalizers and the other end is connected to a control input that adjusts each of the at last two equalizers, and wherein the adaptive feedback circuit comprises a low pass filter and a differential power detector, the differential power detector being configured to compare the output of the at least two equalizers with an output of the low pass filter to determine the control input, and the low pass filter being configured to filter the output of the at leas two equalizers;
wherein the lossy channel and the at least two equalizers a connected in series;
wherein the lossy channel has a frequency response with a roll-off characteristic;
wherein automatically tuning the equalization function includes setting the peaking frequencies of each equalizer to be different from one another, and an overall frequency response of the equalization function ahs a roll-up characteristic configured to compensate for channel loss.

6. The high speed data transmission system of claim 5 , wherein the at least two equalizers are continuous-time linear equalizers.

7. The high speed data transmission system of claim 5 , wherein the peaking frequencies of each of the at least two equalizers is determined from the roll-off characteristic of the lossy channel.

8. The high speed data transmission system of claim 5 , wherein each of the at least two equalizers is independently enabled and disabled.

9. The high speed data transmission system of claim 5 , wherein the lossy channel is an electrical interconnect.

10. The high speed data transmission system of claim 5 , wherein the lossy channel is a fiber optic interconnect with a photodetector.

11. A method of reducing channel loss in high data rate transmission, the method comprising:
determining a frequency response of a lossy channel;
connecting the lossy channel to at least two equalizers in a signal path;
connecting at least one gain stage in the signal path, wherein the at least one gain stage is interspersed between two consecutive equalizers of the at least two equalizers, the least one gain stage being configured to compensate for gain loss between equalization stages corresponding to the equalizers; and
connecting an adaptive feedback circuit to the signal path, wherein the adaptive feedback circuit is configured to provide an adaptive feedback control loop which automatically tunes an equalization function associated with the at least two equalizers and the at least one gain stage, wherein one end of the adaptive circuit is connected to an output of the signal path and the other end is connected to a control input that adjusts each of the at least two equalizers;
wherein automatically tuning the equalization function includes setting the peaking frequencies of each equalization stage to be different from one another, and an overall frequency response of the equalization function has a roll-up characteristic configured to compensate for channel loss.

12. The method according to claim 11 , wherein the at least two equalizers are continuous-time linear equalizers.

13. The method according to claim 11 , wherein the peaking frequencies of each of the at least two equalizers is determined from a roll-off characteristic of the lossy channel.

14. The method according to claim 11 , wherein each of the at least two equalizers is independently enabled and disabled.

15. The method according to claim 11 , wherein the lossy channel is an electrical interconnect.

16. The method according to claim 11 , wherein the adaptive feedback circuit determines a control signal to the control input by comparing a high-frequency signal output of the at least two equalizers with a low-frequency signal output of the at least two equalizers.

17. The method according to claim 11 , wherein the lossy channel is a fiber optic interconnect with a photodetector.

18. The method according to claim 11 , wherein the adaptive feedback circuit comprises a low pass filer and a differential power detector, the differential power detector configured to compare the output of the signal path with an output of the low pass filter to determine the control put, and the low pass filter configured to filer the output of the signal path.

Assignees

• Univ Hong Kong Sci & Tech

Inventors

• Pan Quan
• Yue Chik Patrick

Classifications

• H04L25/03019 Primary

  adaptive, i.e. capable of adjustment during data reception · CPC title

• H04L25/03057

  with a recursive structure (H04L25/03031 takes precedence) · CPC title

• H04L25/03885

  adaptive · CPC title

• H04L25/03159

  operating in the frequency domain (H04L25/03165, H04L25/03178 take precedence) · CPC title