Multi-Band RF Matching Network for Reduced Band Loading

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Solution Overview

Problem

In multi-band RF circuits, band loading occurs due to coupling between active and non-active frequency bands, leading to insertion loss and energy suckout in the active band, which is difficult to isolate in miniaturized mobile devices without increasing the module size.

Innovation Solution

The implementation of a non-active band load impedance, achieved through a select switch input impedance that prevents standing waves by using a shunt path, a shunt capacitor, or a passive impedance circuit, to reduce coupling and resonance in non-active paths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If components are miniaturized to reduce device size, then device compactness is improved, but signal isolation between RF signal paths deteriorates causing band loading

Engineering Contradiction:

Improvedevice sizeVSAvoidband loading

Core Design Contradiction:

Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

A matching network is introduced as an intermediary component between the non-active power amplifier and the select switch. This matching network includes a load impedance specifically designed to prevent resonance in the non-active RF signal path, thereby eliminating the harmful coupling effect while allowing compact component placement.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Volume of moving object

If RF signal paths are closely coupled to save space, then device compactness is improved, but insertion loss in active signal paths increases due to coupling

Engineering Contradiction:

Improvemodule sizeVSAvoidinsertion loss

Core Design Contradiction:

Volume of moving objectVSLoss of energy

Solution Approach 1:

The coupling effect that causes harmful resonance is converted into a beneficial solution by designing the matching network's load impedance to deliberately create a non-resonant condition in the non-active path. This transforms the potential harmful coupling into a mechanism that actively prevents energy loss in the active signal path.

Inventive Principle:

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

3Loss of energy

If band loading is reduced through better isolation, then insertion loss is reduced, but device complexity increases

Engineering Contradiction:

Improveinsertion lossVSAvoidcircuit complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The matching network is merged with the existing RF signal path components rather than being added as a separate isolation module. The load impedance is integrated into the matching network that already exists in the non-active path, reducing overall device complexity while effectively preventing band loading.

Inventive Principle:

Principle #5Merging (Combining)

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 approach effectively reduces band loading without significant impact on other performance parameters, maintaining efficient RF signal transmission across multiple frequency bands in compact mobile device designs.

Implementation Method 1

prevent a resonance in the second RF signal path due to coupling with the first RF signal path

Methodology Applied

Scientific EffectResonance: Resonance

Implementation Method 2

coupling from one signal path to another can result in insertion loss

Methodology Applied

Scientific EffectElectromagnetic coupling:

Data Source

PatentUS10623046B2Multi-band device with reduced band loading

Publication Date: 2020.04.14 SKYWORKS SOLUTIONS INC

AI summary

In an embodiment, an apparatus includes a first radio frequency (RF) signal path and a second RF signal path. The first RF signal path can provide a first RF signal when active and the second RF signal path can provide a second RF signal when active. The second RF signal path can include a matching network with a load impedance configured to prevent a resonance in the second RF signal path due to coupling with the first RF signal path when the first RF signal path is active.