Analog Interference Cancellation in Communication Transceivers

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Solution Overview

Problem

Data communication systems using twisted pairs of wires face significant interference issues, particularly with far-end crosstalk, which is not typically cancelled due to high complexity, leading to a low signal-to-noise ratio and high power consumption in analog-to-digital converters required for noise cancellation.

Innovation Solution

A transceiver architecture that includes a digital compensation circuit to generate a digital interference signal, a digital-to-analog converter to convert this signal into an analog interference signal, and an analog filter to subtract this signal from the received communication signal, reducing the dynamic range and allowing for lower resolution analog-to-digital converters with reduced power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If far-end crosstalk cancellation is implemented in the 10GBASE-T standard, then the signal-to-noise ratio is improved, but the device complexity increases significantly

Engineering Contradiction:

Improvesignal-to-noise ratioVSAvoidcancellation circuitry complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces an analog interference signal as an intermediary element that represents the far-end crosstalk. This analog signal is generated by a digital-to-analog converter from a digital interference signal, and then subtracted from the received signal in the analog domain before ADC conversion. This intermediary approach allows FEXT cancellation without requiring complex digital signal processing, thus improving SNR while avoiding excessive device complexity.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If high resolution analog-to-digital converters are used for noise cancellation, then the measurement precision is improved, but the power consumption increases

Engineering Contradiction:

ImproveADC resolutionVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent performs interference cancellation in the analog domain before the signal enters the ADC. By subtracting the analog interference signal from the received signal prior to conversion, the dynamic range of the signal is reduced. This preliminary action allows the use of lower resolution ADCs (reducing bit depth by approximately 2 bits) while maintaining measurement precision, thereby significantly reducing power consumption.

Inventive Principle:

Principle #10Preliminary action

3Measurement precision

If deterministic noise sources are cancelled in the digital domain, then the measurement precision is improved, but the device complexity and power consumption increase

Engineering Contradiction:

Improvesignal qualityVSAvoidcancellation circuitry

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex digital signal processing operations with simpler analog signal processing. Instead of performing interference cancellation through complex digital algorithms after ADC conversion, the invention uses analog subtraction of the interference signal in the analog domain. This substitution of digital mechanics with analog mechanics achieves the same measurement precision improvement while dramatically reducing device complexity and power consumption.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach effectively cancels deterministic interference sources in the analog domain, reducing the dynamic range of the signal and lowering the power consumption of analog-to-digital converters by approximately 2 bits, resulting in a significant power saving while maintaining signal quality.

Implementation Method 1

a digital-to-analog converter (DAC) to convert the digital interference signal into a corresponding analog interference signal

Methodology Applied

Scientific EffectDigital-to-Analog Conversion:

Implementation Method 2

a subtractor to subtract the analog interference signal from the analog communication signal

Methodology Applied

Scientific EffectSignal Subtraction:

Implementation Method 3

an analog filter to filter the analog communication signal having the analog interference signal subtracted therefrom

Methodology Applied

Scientific EffectAnalog Filtering: Filter (electronic)

Data Source

PatentUS7706434B1Method and apparatus for cancelling interference in a communication system

Publication Date: 2010.04.27 MARVELL ASIA PTE LTD

AI summary

Methods and systems for cancelling interference in an analog communication signal are provided. The method includes receiving an analog communication signal including interference caused by a deterministic interference source, generating a digital interference signal corresponding to the interference caused by the deterministic interference source, converting the digital interference signal into a corresponding analog interference signal, and subtracting the analog interference signal from the analog communication signal.