Monolithic Antenna Switch-Diplexer Integration for RF Isolation

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Solution Overview

Problem

Existing diplexer fabrication processes face challenges in achieving high Q-factor, reducing electromagnetic coupling, and optimizing size and cost-effectiveness, particularly in mobile RF transceivers with complex circuit functions.

Innovation Solution

Monolithic integration of an antenna switch and diplexer on a silicon-on-insulator (SOI) layer, using a resistive substrate and a Faraday cage structure to minimize electromagnetic coupling and reduce costs, with fabrication through FEOL, MOL, and BEOL processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If separate discrete components are used for antenna switch and diplexer, then each component can be optimized independently, but the overall device size, component count, and assembly complexity increase

Engineering Contradiction:
ImproveIndependent component optimizationVSAvoidAssembly complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent combines the antenna switch and diplexer into a single integrated device fabricated on one substrate. The switch portion and diplexer portion share common substrate real estate and can share common RF interfaces, eliminating the need for separate discrete components and reducing assembly complexity while maintaining independent optimization capabilities through separate design regions.

Inventive Principle:
Principle #5Merging (Combining)

2Adaptability or versatility

If separate discrete components are used for antenna switch and diplexer, then design flexibility is maintained, but the overall device footprint and number of RF interfaces increase

Engineering Contradiction:
ImproveDesign flexibilityVSAvoidDevice footprint
Core Design Contradiction:
Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The integrated device nests the switch portion and diplexer portion within a shared substrate area. The switch portion can be positioned to share RF interfaces with the diplexer portion, allowing compact nesting that reduces the overall device footprint while maintaining the functional independence and design flexibility of each component.

Inventive Principle:
Principle #7Nested doll (Nesting)

3Adaptability or versatility

If multiple discrete components are assembled, then functional modularity is achieved, but manufacturing steps and assembly processes become more complex

Engineering Contradiction:
ImproveFunctional modularityVSAvoidManufacturing steps
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent merges the manufacturing processes by fabricating both the switch portion and diplexer portion in the same semiconductor fabrication process on a single substrate. This eliminates multiple assembly steps while maintaining functional modularity through separate design regions that can be independently optimized and configured.

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

Enhances RF performance by reducing electromagnetic coupling and cost, while maintaining high Q-factor and compact size, thus improving efficiency and reducing manufacturing complexity.

Implementation Method 1

a Faraday cage structure to minimize electromagnetic coupling

Methodology Applied
Scientific EffectFaraday cage: Faraday Cage

Implementation Method 2

Monolithic integration of an antenna switch and diplexer on a silicon-on-insulator (SOI) layer, using a resistive substrate

Methodology Applied
Scientific EffectElectrical insulation: Electrical Resistance

Data Source

PatentEP3403278B1Monolithic integration of antenna switch and diplexer
Publication Date: 2026.02.11 QUALCOMM INC
  • EP3403278B1 patent drawingFigure 1A
  • EP3403278B1 patent drawingFigure 1B
  • EP3403278B1 patent drawingFigure 2A~2B

AI summary

An integrated radio frequency (RF) circuit structure may include a resistive substrate material and a switch. The switch may be arranged in a silicon on insulator (SOI) layer supported by the resistive substrate material. The integrated RF circuit structure may also include an isolation layer coupled to the SOI layer. The integrated RF circuit structure may further include a filter, composed of inductors and capacitors. The filter may be arranged on a surface of the integrated RF circuit structure, opposite the resistive substrate material. In addition, the switch may be arranged on a first surface of the isolation layer.