Equalizer Common-Mode Adaptation for Baseline Wander Correction

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Solution Overview

Problem

Baseline wander in communication channels, caused by AC coupling and imbalanced data patterns, leads to common mode drift and power consumption issues in receiver circuits, making it difficult to accurately compensate for signal drift and maintain signal integrity.

Innovation Solution

An equalizer circuit with a baseline wander detection and correction mechanism that determines the average magnitude of data symbols over time, adjusts the common mode operating point, and uses current sources to sink or source current to compensate for drift, thereby mitigating baseline wander effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If AC coupling is used in communication channels, then signal transmission is enabled, but baseline wander and common mode drift occur

Engineering Contradiction:

Improvesignal transmissionVSAvoidcommon mode stability

Core Design Contradiction:

SpeedVSStability of the object's composition

Solution Approach 1:

The patent implements a feedback mechanism where the common mode level is continuously detected from the received signal, and control signals are generated to adjust the common mode operating point of the equalizer circuit. This closed-loop feedback system compensates for baseline wander by dynamically adjusting the common mode level based on detected deviations, thereby maintaining stability despite AC coupling.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes the common mode operating point parameter of the equalizer circuit dynamically. By adjusting the common mode level in response to detected baseline wander, the system adapts the operating parameters to compensate for signal drift, allowing AC coupling to function while maintaining common mode stability.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If conventional baseline wander compensation is used, then signal drift is corrected, but power consumption increases

Engineering Contradiction:

Improvesignal drift correctionVSAvoidpower consumption

Core Design Contradiction:

Stability of the object's compositionVSUse of energy by moving object

Solution Approach 1:

The system uses the received signal itself to detect the common mode level and generate correction signals, rather than requiring separate high-power calibration signals or external reference sources. The equalizer circuit leverages its own input signal to perform self-diagnosis and self-correction of baseline wander, reducing additional power consumption.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent implements periodic updating of the common mode operating point rather than continuous high-power adjustment. By sampling the common mode level at appropriate intervals and adjusting when necessary, the system achieves effective drift correction while minimizing power consumption compared to continuous adjustment schemes.

Inventive Principle:

Principle #19Periodic action

3Adaptability or versatility

If AC coupling is used, then communication channel flexibility is improved, but measurement precision of signal level deteriorates

Engineering Contradiction:

Improvecommunication channel flexibilityVSAvoidsignal level accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent uses feedback to continuously monitor the common mode level of the received signal and generate control signals that adjust the equalizer's common mode operating point. This feedback mechanism compensates for baseline wander caused by AC coupling, thereby restoring measurement precision of signal levels while maintaining the flexibility benefits of AC coupling.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces direct electrical level measurements with a common mode detection and correction mechanism. Instead of directly measuring absolute signal levels (which is inaccurate with AC coupling), the system detects common mode variations and uses electronic adjustment to compensate, substituting a more reliable measurement approach that works with AC coupled channels.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS10483952B1Baseline wander correction using zero and one mismatch adaptation

Publication Date: 2019.11.19 ORACLE INT CORP

AI summary

A method and an apparatus for correcting baseline wander is disclosed. The method and apparatus may include receiving a serial data stream that encodes a plurality of data symbols, and determining an average magnitude of a first data value included in one or more data symbols of a subset of the plurality of data symbols, and an average magnitude of a second value included in the one of more data symbols of the subset of the plurality of data symbols. A common mode operating point of an equalizer circuit may be adjusted using the average magnitude of the first data value and the average magnitude of the second data value.