Dual-Stage RF Switch Assembly for High-Power Isolation

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Solution Overview

Problem

Conventional RF switch circuits face challenges in maintaining high isolation performance, especially at high power levels, due to voltage swings that can induce electrical breakdown and unintended conduction between switch terminals.

Innovation Solution

The RF circuit employs a dual-stage RF switch assembly with a first stage configured to attenuate signal power or isolate the output node from the input node in the off state, ensuring high isolation and low insertion loss even at high power levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If conventional RF switch circuits are used at high power levels, then the switch can handle high input power, but isolation performance deteriorates due to voltage swing-induced electrical breakdown and unintended conduction

Engineering Contradiction:
Improveinput power handling capabilityVSAvoidisolation performance
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The RF switch circuit is divided into two distinct stages: a first RF switch stage and a second RF switch stage. The first stage handles high-power signals and provides attenuation/isolation, while the second stage provides additional isolation. This segmentation allows each stage to be optimized for its specific function, with the first stage protecting the second stage from high-power-induced breakdown, thereby maintaining isolation performance at high power levels.

Inventive Principle:
Principle #1Segmentation

2Device complexity

If a single-stage RF switch is used, then the device complexity is low, but isolation performance deteriorates at high power levels due to voltage swing

Engineering Contradiction:
Improveswitch circuit structureVSAvoidisolation performance
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The RF switch circuit is divided into two distinct stages: a first RF switch stage and a second RF switch stage. The first stage handles high-power signals and provides attenuation/isolation, while the second stage provides additional isolation. This segmentation allows each stage to be optimized for its specific function, with the first stage protecting the second stage from high-power-induced breakdown, thereby maintaining isolation performance at high power levels.

Inventive Principle:
Principle #1Segmentation

3Reliability

If the RF switch is in the off state to provide isolation, then signal conduction between input and output is minimized, but voltage swing still occurs across the switch terminals at high power levels causing electrical breakdown

Engineering Contradiction:
Improveisolation performanceVSAvoidvoltage swing-induced electrical breakdown
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The first RF switch stage is positioned upstream to preemptively attenuate or isolate high-power signals before they reach the second RF switch stage. This preliminary action prevents the voltage swing that would otherwise occur across the second stage switch terminals, eliminating the condition that leads to electrical breakdown and maintaining reliable isolation performance.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4535664A1Radiofrequency circuit, radiofrequency system and method for a radiofrequency circuit
Publication Date: 2025.04.09 INFINEON TECHNOLOGIES AG
  • EP4535664A1 patent drawingFigure 1a~1b
  • EP4535664A1 patent drawingFigure 2a
  • EP4535664A1 patent drawingFigure 2b

AI summary

It is proposed an RF circuit comprising an input node configured to receive an RF signal, an output node configured to output the RF signal, an RF switch assembly coupled between the input node and the output node, wherein the RF switch assembly is configured to selectively connect or disconnect the input node and the output node, and wherein the RF switch assembly comprises a first stage comprising a first RF switch and a second stage comprising a second RF switch, wherein the first stage is configured, in an off state of the RF switch assembly in which the first stage and the second stage are in an off state, to attenuate a signal power of the RF signal or isolate the output node against the input node.