RF Ground Inductance Compensation for Duplexer Signal Isolation

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Solution Overview

Problem

Inadequate ground connections in duplexers for mobile terminal devices lead to reduced transmitter/receiver insulation due to voltage drops across inductance, affecting signal paths and filter properties, especially in miniaturized multiband applications where limited feed-throughs restrict ground connection to the module.

Innovation Solution

An RF configuration with a coupling element that electromagnetically couples to the ground connection, decouples and feeds the induced coupling current back into the signal path, compensating for voltage drops caused by inductance in the ground connection, thereby reducing crosstalk between components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the module is miniaturized with limited surface area, then the device size is reduced, but the number of feed-throughs for ground connection is limited, causing inadequate ground connection

Engineering Contradiction:

Improvemodule sizeVSAvoidground connection quality

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

A coupling element is introduced as an intermediary component that electromagnetically couples to the ground connection. This coupling element captures the coupling current induced by ground current flow and feeds it into the signal path, thereby mediating the effect of inadequate ground connection and compensating for voltage drops caused by ground inductance.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Volume of moving object

If the ground connection has finite inductance, then the module can be miniaturized, but voltage drops affect all signal paths connected to this ground, reducing transmitter/receiver insulation

Engineering Contradiction:

Improvemodule sizeVSAvoidvoltage drop effect on signal paths

Core Design Contradiction:

Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

The coupling element provides a feedback mechanism by capturing the coupling current that is naturally induced in the ground connection and feeding it back into the signal path. This feedback compensates for the voltage drops caused by ground inductance, effectively counteracting the harmful effects of finite inductance on signal path insulation.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The coupling current induced by ground current flow, which was previously a source of interference and voltage drops, is now utilized beneficially. The coupling element captures this coupling current and feeds it into the signal path in a controlled manner, converting the harmful effect of ground inductance into a compensating mechanism that improves transmitter/receiver insulation.

Inventive Principle:

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

3Reliability

If more feed-throughs are added to improve ground connection, then ground connection quality improves, but the module surface area requirement increases

Engineering Contradiction:

Improveground connection qualityVSAvoidmodule surface area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The coupling element serves as an intermediary that compensates for inadequate ground connection without requiring additional feed-throughs. By electromagnetically coupling to the existing ground connection and feeding the induced coupling current into the signal path, it achieves improved transmitter/receiver insulation while maintaining the limited surface area constraint.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Reliability

If the ground connection inductance is reduced, then voltage drops are minimized, but the coupling element cannot compensate for inductance effects

Engineering Contradiction:

Improvesignal path insulationVSAvoidground connection simplicity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The coupling element implements a feedback mechanism that actively compensates for voltage drops caused by ground inductance. By capturing the coupling current induced by ground current flow and feeding it into the signal path, the system maintains improved signal path insulation while allowing the ground connection to remain simple with finite inductance.

Inventive Principle:

Principle #23Feedback

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 configuration significantly reduces or eliminates crosstalk between RF components by compensating for voltage drops, maintaining effective insulation and filter properties even with finite inductance in the ground connection, ensuring low crosstalk levels.

Implementation Method 1

a coupling element which electromagnetically couples to the ground connection. The coupling current induced in the coupling element when current flows through the ground connection

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS20090284328A1Configuration Having an RF Component and a Method for Compensation of Linking Inductance

Publication Date: 2009.11.19 SNAPTRACK INC

AI summary

In a configuration with at least one RF component disposed in a signal path and including a ground connection to an external circuit environment, a coupling element is provided which electromagnetically couples to at least part of the ground connection and at the same time decouples a coupling current. By suitably feeding this coupling current back into the signal path of the component, the negative influence of the inductance of the ground connection on the signal path is thus compensated for.