DSL Signal Circuit Passive Echo Canceller

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Solution Overview

Problem

Existing digital subscriber line signal transmitting and receiving circuits face challenges with echo cancellation due to bandwidth limitations of active components and impedance matching issues, leading to signal interference and increased circuit costs.

Innovation Solution

A signal transmitting and receiving circuit using passive components, including a three-winding transformer and impedance units, to simulate the characteristic impedance of both the hybrid circuit and telecommunication loop, allowing for flexible adjustment of DC gain and pole frequency, and enabling shared echo cancelling circuits for asymmetric and very high speed digital subscriber lines.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If active components are used in the echo cancelling circuit, then the transfer function can be easily simulated, but bandwidth limitations and zeroes/poles cause poor impedance matching in certain frequency ranges

Engineering Contradiction:

Improveease of simulating transfer functionVSAvoidimpedance matching performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent replaces active components (electronic system) with passive components including resistors, capacitors, and inductors (passive system) to construct the echo cancelling circuit. This substitution eliminates bandwidth limitations and stability issues of active components while maintaining the ability to simulate transfer functions through proper component configuration and impedance matching.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If a conventional two-winding transformer is used, then the structure is simple, but voltage swing is lost on impedance units and higher working voltage is required

Engineering Contradiction:

Improvetransformer structure complexityVSAvoidvoltage swing loss

Core Design Contradiction:

Device complexityVSUse of energy by moving object

Solution Approach 1:

The patent segments the transformer into three separate windings (first winding for transmitting signal, second winding for receiving signal, third winding for impedance matching) instead of using a conventional two-winding transformer. This segmentation allows independent optimization of each winding's function, eliminating voltage swing loss on impedance units while maintaining structural simplicity through modular design.

Inventive Principle:

Principle #1Segmentation

3Adaptability or versatility

If the same echo cancelling circuit is used for both ADSL and VDSL, then circuit cost is reduced, but frequency band differences require flexible impedance simulation

Engineering Contradiction:

Improvecircuit reusabilityVSAvoidimpedance simulation flexibility

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent designs the echo cancelling circuit with universal passive components (resistors, capacitors, inductors) that can be configured to simulate different transfer functions for both ADSL and VDSL frequency bands. The three-winding transformer and impedance units provide flexible impedance simulation capabilities that adapt to different frequency requirements without requiring separate circuits, achieving both cost reduction and adaptability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 solution improves signal-to-noise ratio by maintaining higher signal amplitude and reducing circuit costs, while allowing the same echo cancelling circuit to be used for both ADSL and VDSL, enhancing flexibility and efficiency.

Implementation Method 1

a first winding and a third winding of the transformer transmit an output signal to a telecommunication loop by electromagnetic coupling

Methodology Applied

Scientific EffectElectromagnetic coupling: Electromagnetic Induction

Implementation Method 2

the third winding and the second winding transmits the input signal to the signal receiving module by electromagnetic coupling

Methodology Applied

Scientific EffectElectromagnetic coupling: Electromagnetic Induction

Data Source

PatentUS9312912B2Signal transmitting and receiving circuit of digital subscriber line

Publication Date: 2016.04.12 REALTEK SEMICON CORP

AI summary

This invention discloses a signal transmitting and receiving circuit of a digital subscriber line used for transmitting an output signal to a telecommunication loop or receiving an input signal from the telecommunication loop. The signal transmitting and receiving circuit comprises a transformer, which is coupled to the telecommunication loop; a signal transmitting module, which is coupled to the transformer, for generating the output signal; a signal receiving module, which is coupled to the transformer, for processing the input signal; an echo cancelling circuit, comprising passive components and having two ends, one of which is coupled to the signal transmitting module and the transformer, the other is coupled to the signal receiving module and the transformer. The output signal is transmitted to the telecommunication loop via the electromagnetic coupling of the transformer, and the input signal is received by the signal receiving module by the electromagnetic coupling of the transformer.