Locking Pattern for SERDES Signal Integrity

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Solution Overview

Problem

High-speed serial link interfaces like SERDES face challenges in maintaining signal integrity due to recurring patterns, which lead to increased bit error rates, as conventional techniques like bit-stuffing are ineffective for multi-bit repetitive patterns.

Innovation Solution

A locking pattern is generated and inserted into the data stream, comprising locking symbols and a random bit pattern, which allows the receiver to lock onto and ignore recurring sequences, enabling Decision Feedback Equalizer (DFE) adaptation and maintaining signal integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If bit-stuffing is used to break recurring bit patterns, then single-bit patterns are effectively broken, but multi-bit repetitive patterns cannot be handled effectively

Engineering Contradiction:

Improvebit error rateVSAvoidhandling capability for different pattern types

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The invention changes the parameter of pattern-breaking from single-bit insertion (bit-stuffing) to multi-bit pattern insertion (locking patterns). By transforming the granularity and complexity of the inserted pattern, the system can effectively handle both single-bit and multi-bit repetitive patterns, thereby improving versatility while maintaining reliability.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If locking pattern with random bits is inserted to break recurring sequences, then DFE equalization is enabled, but data stream complexity increases

Engineering Contradiction:

Improvesignal integrityVSAvoiddata stream structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The locking pattern acts as an intermediary element inserted into the data stream to mediate between the transmitter and receiver. This intermediary pattern provides the necessary random bits for DFE equalization while being systematically removable at the receiver end through pattern recognition, thus improving signal integrity without creating permanent complexity in the data stream structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If receiver locks onto locking pattern to ignore recurring sequences, then equalization is maintained, but pattern recognition complexity increases

Engineering Contradiction:

ImproveDFE equalizationVSAvoidpattern identification

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The locking pattern is designed with a predetermined structure that includes a recognizable header or signature sequence. This preliminary structural design allows the receiver to quickly identify and lock onto the pattern without requiring complex real-time analysis, thereby maintaining DFE equalization while minimizing pattern recognition complexity through advance structural planning.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS7397397B1Method and system for breaking repetitive patterns to reduce transmission errors

Publication Date: 2008.07.08 CISCO TECHNOLOGY INC

AI summary

A method and a system for communicating data in a communication channel are provided. The method includes the identification of a sequence of bits recurring in the data, and generating a locking pattern. The locking pattern includes locking symbols and a random bit pattern. The method also includes sending the locking pattern within the data. The locking pattern is received by a receiver and is used to lock the receiver and ignore the recurring bit sequence.