Transceiver Impedance Switching to Reduce Shared-Medium Reflections

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Solution Overview

Problem

Impedance mismatches between communications systems and shared media in cable networks cause signal reflections and spurious emissions, leading to signal degradation and errors, especially during mode transitions in transceivers.

Innovation Solution

Implementing a method where transceivers dynamically switch between transmission, receiving, and load paths to maintain a consistent output impedance, using switching circuitry and controllers to couple the output to either the transmission amplifier or load path, and enabling/disabling amplifiers based on operational modes to reduce impedance variations and attenuate unwanted signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If transceivers switch between transmission and receiving modes dynamically, then communication versatility is improved, but impedance mismatch and signal reflections worsen

Engineering Contradiction:

Improvecommunication mode flexibilityVSAvoidsignal reflections

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

A switching network acts as an intermediary between the amplifier and the shared medium, dynamically connecting different amplifier ports (transmit, receive, or load) to the medium based on operational mode. This mediator ensures impedance matching is maintained during mode transitions, preventing signal reflections while enabling versatile communication operations.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system dynamically reconfigures its impedance-matching configuration during mode transitions by activating different amplifier ports and adjusting the switching network. This dynamic adaptation ensures that whether in transmit, receive, or standby mode, the amplifier presents the correct impedance to the shared medium, eliminating reflections caused by static impedance mismatches.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If transceivers switch between transmission and receiving modes dynamically, then communication versatility is improved, but signal degradation and errors worsen

Engineering Contradiction:

Improvecommunication mode flexibilityVSAvoidsignal quality

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The switching network serves as a mediator that ensures continuous impedance matching between the amplifier and shared medium during mode transitions. By dynamically routing signals through appropriate amplifier ports and maintaining proper loading conditions, it prevents signal degradation and errors that would otherwise occur during transitions.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system proactively manages impedance matching before and during mode transitions by pre-configuring the switching network and amplifier ports. This beforehand preparation ensures that impedance discontinuities are minimized during transitions, cushioning against signal degradation and maintaining high signal quality throughout mode changes.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Device complexity

If amplifier output impedance is allowed to vary with operational mode, then device complexity is reduced, but signal reflections and spurious emissions worsen

Engineering Contradiction:

Improveimpedance control complexityVSAvoidspurious emissions

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

The switching network acts as an intermediary that manages the complexity of impedance control by dynamically connecting different amplifier ports to the shared medium. This mediator handles the complexity of maintaining proper impedance across different modes, allowing the amplifier to operate in various modes while preventing spurious emissions through proper impedance matching.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The amplifier is designed with multi-functionality, capable of operating in transmit, receive, and standby modes while maintaining impedance matching through the switching network. This universal design allows a single amplifier to perform multiple functions without generating spurious emissions, as the switching network ensures proper impedance presentation regardless of operational mode.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS10560202B2Reducing impedance discontinuities on a shared medium

Publication Date: 2020.02.11 SKYWORKS SOLUTIONS INC

AI summary

Systems and methods are provided for reducing the effects of an impedance mismatch between a communications system and a shared communications medium. A communication system, such as a transceiver within a cable modem, switches between various operating modes including a transmit mode, a receive mode, and a standby mode. The standby mode may be used while the transceiver is in an idle state between modes, such as while changing an amplifier gain states in between transmissions. While transitioning between modes, the impedance presented by the communications system can temporarily fluctuate causing unwanted signal reflections to propagate out of the communications system and on to the shared medium. Circuitry within the communications system, such as transmission circuitry including an adjustable attenuator, may be placed into a hybrid attenuation-isolation mode during the transition causing the magnitude of any unwanted signal reflections to be attenuated and reducing the impact on the shared medium.