LC Distributed Matching for RF Switch Impedance Equalization

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The increasing complexity of RF front-ends in mobile devices, driven by new communication standards like Advanced LTE and 5G, leads to path-to-path variation in RF performance, particularly insertion loss, return loss, and linearity, resulting in unbalanced device-level RF performance where the worst performing switch path limits the entire RF system.

Innovation Solution

The implementation of a branched structure in RF cross-switch transmission lines with mutual and self-inductance portions to equalize impedance differences between paths, using a compensation effect generated by the mutual inductance configuration to minimize the inductance difference between connection paths, thereby optimizing switch performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If more complex switching devices (higher pole and throw count) are used to support multiple antennas and communication standards, then the capability to connect multiple paths is improved, but the path-to-path variation in RF performance (insertion loss, return loss, linearity) worsens

Engineering Contradiction:

Improvecapability to connect multiple pathsVSAvoidpath-to-path variation in RF performance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies local quality by introducing individual matching networks (LC circuits) to each transmission line path independently. Each path receives tailored impedance matching components (inductors and capacitors) configured to compensate for its specific impedance characteristics, thereby equalizing RF performance across all paths while maintaining the high adaptability of the multi-pole multi-throw switch structure

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs parameter changes by adjusting the values of inductors and capacitors in the matching networks to optimize impedance matching for each path. By varying these electrical parameters, the patent equalizes the RF performance parameters (insertion loss, return loss, linearity) across different switch paths, resolving the path-to-path variation issue

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If more complex switching devices are used to support multiple antennas, then the versatility of the RF front-end is improved, but the device complexity increases

Engineering Contradiction:

Improvecapability to connect multiple pathsVSAvoidswitching device complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing the RF front-end into multiple independent transmission line paths, each with its own matching network. This modular approach allows each segment to be optimized independently while maintaining overall system versatility, managing the complexity through structured decomposition rather than monolithic design

Inventive Principle:

Principle #1Segmentation

3Device complexity

If the worst performing switch path is allowed to limit the RF system, then the device complexity is reduced, but the overall RF system performance deteriorates

Engineering Contradiction:

Improveswitching device complexityVSAvoidoverall RF system performance

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent applies local quality by introducing individual matching networks to each transmission line path. Each path receives customized impedance matching components (inductors and capacitors) that compensate for its specific impedance characteristics, thereby equalizing RF performance across all paths and preventing the worst-performing path from limiting overall system performance

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs feedback principles through the design of matching networks that are configured based on measured or simulated impedance characteristics of each path. The matching component values are selected to compensate for path-specific variations, creating a feedback loop where path performance information is used to optimize the matching network configuration

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 approach significantly improves the RF performance parameters on the worst performing paths, achieving a more balanced system design by minimizing the impedance difference between the best and worst case paths, leading to improved insertion loss, isolation, and return loss across all switch paths.

Implementation Method 1

adding a first mutual inductance portion to a first self-inductance portion of a first transmission line; and adding a second mutual inductance portion to a second self-inductance portion of a second transmission line

Methodology Applied

Scientific EffectMutual inductance: Electromagnetic Induction

Data Source

PatentUS11528041B2LC distributed matching for equalized cross-switch RF performance

Publication Date: 2022.12.13 INFINEON TECHNOLOGIES AG

AI summary

A method of manufacturing an RF switch includes adding a first mutual inductance portion to a first self-inductance portion of a first transmission line; and adding a second mutual inductance portion to a second self-inductance portion of a second transmission line, wherein values of the first and second mutual inductance portions and values of the first and second self-inductance portions equalize an impedance difference between the first transmission line and the second transmission line.