Integrated Echo Cancellation and Equalization Front-End Circuit

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Solution Overview

Problem

Conventional data processing systems face degrading signal-to-residual echo and signal-to-noise ratios at higher cable lengths due to ineffective echo cancellation and automatic gain control in full-duplex systems like Gigabit Ethernets.

Innovation Solution

A communications cabling front-end architecture that combines echo-cancellation and equalization functions at the same point, using a conditioning circuit to minimize mismatches and noise, with a digital-to-analog converter controlling equalization to provide enhanced signal boosting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional separate echo cancellation and equalization circuits are used, then device complexity is reduced, but signal-to-residual echo ratio and signal-to-noise ratio degrade at higher cable lengths

Engineering Contradiction:

Improvesignal-to-residual echo ratioVSAvoidcircuit architecture

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the echo cancellation circuit and equalization circuit into a single integrated conditioning circuit. The echo canceller subtracts the transmit signal replica from the received signal, and the equalizer simultaneously compensates for cable frequency response, achieving both functions in one unified structure rather than separate stages.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The conditioning circuit performs multiple functions simultaneously: echo cancellation, equalization, and automatic gain control. This multi-functional approach allows a single circuit to handle both echo rejection and signal quality optimization, improving performance without proportionally increasing complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If cable equalization is applied to compensate for signal loss, then signal-to-noise ratio improves, but noise amplification increases at higher cable lengths

Engineering Contradiction:

Improvesignal-to-noise ratioVSAvoidnoise amplification

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The echo cancellation is performed before equalization in the signal processing chain. By removing the echo component first, the subsequent equalization operates on a cleaner signal with reduced echo interference, thereby achieving signal compensation without amplifying residual echo noise as much.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses automatic gain control with feedback to dynamically adjust the equalization gain based on the actual signal conditions. This feedback mechanism prevents excessive noise amplification by monitoring the output signal quality and adjusting parameters accordingly.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS7813495B1Apparatus and method for automatic gain control and echo cancellation in a network system

Publication Date: 2010.10.12 NAT SEMICON CORP

AI summary

A communications cabling front-end architecture that achieves solid echo cancellation and lower noise performance by combining an echo-cancellation circuit and an equalizer function at the same point, at the most front-end of the system.