Method and System for Optimum Channel Equalization From a SERDES to an Optical Module

• US 20100221017A1
• Filed: 03/04/2010
• Published: 09/02/2010
• Est. Priority Date: 07/22/2002
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Ghiasi, Ali
• Granted Patent: US 8,693,885 B2
• Time in Patent Office: Days
• US Class Current: 398/149
• CPC Class Codes: H04B 10/25137 using pulse shaping at the transmitter, e.g. pre-chirping or dispersion supported transmission [DST]

Abstract

Certain aspects of a method and system for optimum channel equalization between a host Serializer-Deserializer (SerDes) and an optical module may compensate and reduce dispersion loss along an electrical transmit path of a transmitter and an optical transmit path coupled to the transmitter via pre-emphasis. The data degradation as a result of the dispersion loss along the electrical transmit path of the transmitter and the optical transmit path coupled to the transmitter may be recovered by equalizing signals received via an electrical receive path of a receiver communicatively coupled to the transmitter.

Claims

1-20. -20. (canceled)

21. A method for optical communication, the method comprising:

setting coefficients of a transmit feedforward filter based on a communication channel;

applying pre-emphasis to a transmitted signal using said transmit feedforward filter;

applying equalization to a received signal using a decision feedback equalizer;

adjusting said decision feedback equalizer to compensate for dispersion; and

selectively looping back said transmitted signal to said decision feedback equalizer.

22. The method according to claim 21, wherein said decision feedback equalizer comprises a receive feedback filter.

23. The method according to claim 22, comprising:

generating a feedback filtered signal by said decision feedback equalizer; and

inputting said feedback filtered signal to a decision block.

24. The method according to claim 23, comprising making decisions by said decision block on a symbol by symbol basis.

25. The method according to claim 24, wherein said decision feedback equalizer comprises an adaptive feedforward filter.

26. The method according to claim 25, comprising:

generating a feedforward filtered signal by said adaptive feedforward filter; and

inputting said feedforward filtered signal to said decision block.

27. The method according to claim 21, wherein said transmit feedforward filter comprises three taps and three adjustable coefficients.

28. The method according to claim 21, comprising setting said coefficients of said transmit feedforward filter based on a circuit board channel.

29. The method according to claim 21, comprising looping back said transmitted signal to said decision feedback equalizer, if dispersion loss along an electrical transmit path of said transmitted signal is similar to said dispersion loss along an electrical receive path of said received signal.

30. The method according to claim 29, comprising determining a level of said pre-emphasis based on channel inter-symbol interference (ISI) along one or both of:

said electrical transmit path and/or said electrical receive path.

31. A system for optical communication, the system comprising:

one or more circuits that are operable to set coefficients of a transmit feedforward filter based on a communication channel;

said one or more circuits are operable to apply pre-emphasis to a transmitted signal using said transmit feedforward filter;

said one or more circuits are operable to apply equalization to a received signal using a decision feedback equalizer;

said one or more circuits are operable to adjust said decision feedback equalizer to compensate for dispersion; and

said one or more circuits are operable to selectively loop back said transmitted signal to said decision feedback equalizer.

32. The system according to claim 31, wherein said decision feedback equalizer comprises a receive feedback filter.

33. The system according to claim 32, wherein said one or more circuits in said decision feedback equalizer are operable to generate a feedback filtered signal that is input to a decision block.

34. The system according to claim 33, wherein said one or more circuits in said decision block are operable to make decisions on a symbol by symbol basis.

35. The system according to claim 34, wherein said decision feedback equalizer comprises an adaptive feedforward filter.

36. The system according to claim 35, wherein said one or more circuits in said adaptive feedforward filter are operable to generate a feedforward filtered signal that is input to said decision block.

37. The system according to claim 31, wherein said transmit feedforward filter comprises three taps and three adjustable coefficients.

38. The system according to claim 31, wherein said one or more circuits are operable to set said coefficients of said transmit feedforward filter based on a circuit board channel.

39. The system according to claim 31, wherein said one or more circuits are operable to loop back said transmitted signal to said decision feedback equalizer, if dispersion loss along an electrical transmit path of said transmitted signal is similar to said dispersion loss along an electrical receive path of said received signal.

40. The system according to claim 39, wherein said one or more circuits are operable to determine a level of said pre-emphasis based on channel inter-symbol interference (ISI) along one or both of:

said electrical transmit path and/or said electrical receive path.