System and method of link optimization

Patent metadata

Field	Value
Publication number	US-2016006589-A1
Application number	US-201514741135-A
Country	US
Kind code	A1
Filing date	Jun 16, 2015
Priority date	Jul 1, 2014
Publication date	Jan 7, 2016
Grant date	—

Abstract

A method of characterizing a channel between a transmitter and a receiver (e.g., in a high-speed link) is presented. The method comprises: determining an overall intersymbol interference (ISI) probability density function (PDF) from eye monitor data obtained for a current equalizer setting, extracting a channel ISI PDF for the current equalizer setting from the overall ISI PDF, and generating an overall ISI PDF for a different equalizer setting by using the channel ISI PDF for the current equalizer setting and an impulse response at the different equalizer setting. Based on this characterization, an optimal equalizer setting may be selected among a plurality of equalizer settings on the basis of the channel ISI PDF and the equalizer response functions.

First claim

What is claimed is:

1 . A method of characterizing a channel between a transmitter and a receiver, comprising:
determining an overall intersymbol interference (ISI) probability density function (PDF) from eye monitor data obtained for a current equalizer setting; extracting a channel ISI PDF from the overall ISI PDF by using the current equalizer setting; and generating an overall ISI PDF for a different equalizer setting by using the channel ISI PDF and an impulse response at the different equalizer setting.

2 . The method of claim 1 , wherein the extracting of the channel ISI PDF comprises using an equalizer response function corresponding to the current equalizer setting.

3 . The method of claim 1 , wherein the extracting of the channel ISI PDF comprises deconvoluting the overall ISI PDF with at least one of an impulse PDF corresponding to the transmitter and an impulse PDF corresponding to the equalizer in the current equalizer setting.

4 . The method of claim 1 , wherein the extracting of channel ISI PDF for the current equalizer setting comprises:
applying Fourier transformation to the overall ISI PDF to generate transformed overall ISI PDF; dividing the transformed overall ISI PDF by Fourier transform of impulse PDFs corresponding to the current equalizer setting to generate a quotient; and inverse-Fourier transforming the quotient.

5 . The method of claim 1 , wherein the determining of the overall ISI PDF from eye monitor data comprises using the following equation:

BER
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p
i

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P
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n
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d
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Wherein BER i =P[n>d i ]=Q(d i /σ n ) represents the probability of error due to noise, σ n represents the noise rms power, and p i represents the ISI PDF.

6 . A method of optimizing a high-speed link including an equalizer, the method comprising:
determining a first overall ISI PDF from eye monitor data obtained for a current equalizer setting; extracting a channel ISI PDF from the first overall ISI PDF by using the current equalizer setting; generating a second overall ISI PDF for a different equalizer setting by using the channel ISI PDF; and determining an optimum equalizer setting based on a comparison of the first overall ISI PDF and the second overall ISI PDF.

7 . The method of claim 6 further comprising:
obtaining an impulse response function for the different equalizer setting; and
using the impulse response function with the channel ISI PDF for the generating of the second overall ISI PDF.

8 . The method of claim 6 , wherein determining the optimum equalizer setting comprises:
calculating Bit Error Rate (BER) values for the current equalizer setting and the different equalizer setting; and selecting the setting that results in lowest BER value.

9 . The method of claim 6 , wherein determining the optimal equalizer setting includes:
estimating the second overall ISI PDFs for the different equalizer settings by combining the channel ISI PDF with a corresponding equalizer response function for the different equalizer setting; and selecting the setting associated with either the first overall ISI PDF or the second overall ISI PDFs as the optimal equalizer setting based on which of the two equalizer settings results in a smaller spread of distribution function.

10 . The method of claim 6 , wherein the impulse response function is a Fourier transform function of a PDF that corresponds to the impulse response of the equalizer for the different equalizer setting.

11 . The method of claim 6 , further comprising receiving the first BER values for a plurality of phases, and the optimal equalizer setting is determined for the plurality of phases.

12 . The method of claim 6 , wherein the high-speed link includes a filter at the transmitter, further comprising:
obtaining a plurality of filter response functions corresponding to a plurality of filter settings for the filter at the transmitter; determining an optimal filter setting among the plurality of filter settings on the basis of the channel ISI PDF and the plurality of filter response functions; and providing the optimal filter setting to a filter configured to pre-emphasize the signal before transmitting the signal over a channel.

13 . The method of claim 6 , wherein the equalizer is a Continuous Time Linear Equalizer (CTLE) in the receiver.

14 . The method of claim 13 , wherein the eye monitor data is obtained using a recovered clock signal from a clock data recovery (CDR) unit and an equalized signal from the CTLE.

15 . A system of optimizing a high-speed link including a channel carrying a data signal between a transmitter and a receiver, the system comprising:

Assignees

• Samsung Display Co Ltd

Inventors

• Kamali Jalil

Classifications

• H04L27/01 Primary

  Equalisers {(baseband equalizers at the transmitter end H04L25/03343; in analogue transmission systems H04B3/04, H04B7/005)} · CPC title

• H04L25/03343

  Arrangements at the transmitter end · CPC title

• H04B3/46 Primary

  Monitoring; Testing · CPC title

• H04L25/03885

  adaptive · CPC title

• H04L25/03057

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