RF Multiplexer Wiring Layout to Suppress Electromagnetic Coupling
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Solution Overview
Problem
Existing radio frequency modules suffer from unnecessary electromagnetic field coupling between wirings, leading to deterioration of transmission characteristics due to close proximity of wiring connections, resulting in unintended impedance changes and reduced signal quality.
Innovation Solution
A radio frequency circuit design utilizing a multilayer substrate with series and parallel arm circuits, where the first and second wiring forming the first path are in different layers and do not overlap with the third wiring forming the second path, incorporating impedance variable circuits like switch elements and variable capacitors to control transmission characteristics, and including LC series resonance circuits and acoustic wave resonators to adjust bandpass characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If wirings are arranged close to each other to reduce device area, then area is reduced, but unnecessary electromagnetic field coupling is generated between wirings
Solution Approach 1:
The patent applies multilayer substrate technology to arrange wirings in different layers (three-dimensional space) rather than only in the same plane. Specifically, the first wiring is arranged in a first layer and the second wiring is arranged in a second layer, allowing them to be close in three-dimensional space while avoiding planar overlap that causes electromagnetic coupling. This resolves the contradiction by transitioning from two-dimensional to three-dimensional wiring arrangement.
2Object-affected harmful factors
If wirings are placed in different layers to suppress electromagnetic coupling, then electromagnetic field coupling is reduced, but device complexity increases
Solution Approach 1:
The patent integrates multiple functions into the multilayer substrate structure itself. The substrate simultaneously provides mechanical support, electrical insulation between layers, and defined wiring pathways. By merging these functions into a single integrated structure rather than using separate components, the patent reduces overall device complexity despite using multiple layers for wiring arrangement.
3Reliability
If impedance variable circuits are added to control transmission characteristics, then bandpass characteristic is improved, but device complexity increases
Solution Approach 1:
The patent designs the multilayer substrate to serve multiple functions: it provides mechanical support, electrical insulation, defined wiring pathways, and integration for impedance variable circuits. By making the substrate universal and multi-functional, the patent avoids adding separate structural components that would increase complexity, while still enabling the impedance variable circuits to improve bandpass characteristics.
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 effectively suppresses electromagnetic field coupling, maintaining low transmission loss in the pass band and high attenuation in the attenuation band, thereby enhancing the bandpass characteristic and reducing insertion loss and improving isolation between frequency bands.
Implementation Method 1
a first impedance variable circuit for varying a transmission characteristic of a radio frequency signal between the first input/output terminal and the second input/output terminal
Implementation Method 2
an unnecessary electromagnetic field coupling is generated between both wirings. In this case, there is a problem that a transmission characteristic of the radio frequency signal passing between the first input/output terminal and the second input/output terminal deteriorate
Implementation Method 3
including LC series resonance circuits and acoustic wave resonators to adjust bandpass characteristics
Data Source
AI summary
A radio frequency circuit includes a multilayer substrate, series arm circuits in a first path connecting the input/output terminals (T1 and T2) on the multilayer substrate, a parallel arm circuit in a second path connecting a node on the first path and a ground, a wiring A on the multilayer substrate connected to the input/output terminal (T1) as a part of the first path, a wiring B on the multilayer substrate connected to the input/output terminal (T2) as a part of the first path, and a wiring C on the multilayer substrate as a part of the second path. The parallel arm circuit includes an impedance variable circuit, the wiring A and the wiring B in a layer different from the multilayer substrate. When viewed in a plan view, the wiring C does not overlap with the wiring A and the wiring B.