Hybrid Matching Circuit for Digital Subscriber Loop Echo Suppression

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Solution Overview

Problem

Existing integrated hybrid circuits for digital subscriber loops face challenges in optimizing upstream and downstream rates while effectively reducing echo noise coupled to the receiving circuit from upstream signals, due to inadequate consideration of transmission power, filter bandwidth, and impedance matching.

Innovation Solution

An integrated hybrid circuit with a transmission unit, transceiver coil, transceiver circuit, and hybrid matching circuit that adjusts transmission power and bandwidth based on an adjustment signal generated by the receiving circuit, using selective impedances to match the digital subscriber loop's length and types, and optimizing filter bandwidth to reduce echo noise and enhance signal-to-noise ratio.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If full-duplex technology is used to increase efficiency, then the upstream and downstream rates are improved, but echo noise coupled to the receiving circuit from upstream signals increases

Engineering Contradiction:

Improveupstream and downstream ratesVSAvoidecho noise

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent uses the echo noise generated by full-duplex operation as a feedback signal to adjust the transmission driver's output impedance. By monitoring the actual echo noise and using it to tune the impedance matching network, the system converts the harmful echo into a useful control signal that optimizes both echo suppression and data transmission rates.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent implements dynamic impedance tuning where the transmission driver's output impedance is continuously adjusted based on real-time echo noise levels and signal quality measurements. This dynamic adaptation allows the system to optimize performance under varying operating conditions, balancing echo suppression with maximum upstream and downstream rates.

Inventive Principle:

Principle #15Dynamics

2Reliability

If transmission power is increased to improve signal strength, then the signal-to-noise ratio is improved, but echo noise coupling to the receiving circuit increases

Engineering Contradiction:

Improvesignal-to-noise ratioVSAvoidecho noise coupling

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent dynamically adjusts multiple parameters including transmission driver output impedance, filter bandwidth, and transmission power levels based on real-time signal quality measurements. By coordinating changes in these parameters, the system achieves optimal signal-to-noise ratio while minimizing echo noise coupling to the receiving circuit.

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If filter bandwidth is narrowed to reduce echo noise, then echo noise suppression is improved, but the upstream and downstream rates decrease

Engineering Contradiction:

Improveecho noise suppressionVSAvoidupstream and downstream rates

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The patent implements dynamic filter bandwidth adjustment where the filter characteristics are continuously tuned based on actual signal conditions and echo noise levels. This allows the system to use narrower bandwidth when echo suppression is critical and widen bandwidth when data transmission rates are the priority, optimizing the balance between noise reduction and communication efficiency.

Inventive Principle:

Principle #15Dynamics

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

The solution efficiently suppresses echo noise and optimizes upstream and downstream rates by adjusting transmission power and bandwidth, compensating for signal attenuation and improving the signal-to-noise ratio, thereby enhancing the overall performance of the digital subscriber loop transceiver system.

Implementation Method 1

the transceiver coil 106 transmits the pair of upstream signals to a central office 110 through a twisted pair 108

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

matching circuits 114, 116 are used for matching output impedances of the coils 1042, 1044 to decrease echo noise coupled to the receiving terminal 112 from the pair of upstream signals

Methodology Applied

Scientific EffectImpedance matching: Electrical Impedance Tomography

Data Source

PatentUS8861687B2Integrated hybird circuit applied to a digital subscriber loop and setting method thereof

Publication Date: 2014.10.14 REALTEK SEMICON CORP

AI summary

An integrated hybrid circuit includes a transmission unit, a transceiver coil, a transceiver circuit, a hybrid matching circuit, and a receiving circuit. The transmission unit generates a pair of upstream signals according to a user transmission signal. The transceiver coil transmits the pair of upstream signals to a central office through a pair of twisted pair, and receiving a pair of downstream signals from the central office through the pair of twisted pair. The hybrid matching circuit receives an adjustment signal to adjust selective impedances. The receiving circuit receives the pair of downstream signals from the central office, and generates the adjustment signal according to downstream and upstream rates and signals from the hybrid matching circuit. The transmission unit adjusts transmission power and bandwidth of the transmission unit and the receiving unit adjusts filter bandwidth of the receiving unit according to the adjustment signal for optimizing upstream and downstream rates.