SAW Filter Module Layout for Strong Coupling and Out-of-Band Attenuation
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Solution Overview
Problem
Existing high-frequency modules with surface acoustic wave filters face challenges in achieving sufficient inductive coupling between electrode patterns and inner wiring patterns due to large distances, resulting in inadequate attenuation characteristics outside the pass band.
Innovation Solution
The implementation of a high-frequency module with a surface acoustic wave filter that includes a piezoelectric substrate, an electrode pattern, and a wiring pattern inductively or capacitively coupled across a narrow gap, utilizing a resin member to enhance coupling strength and reduce module size, while a grounded shield electrode minimizes unwanted interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrode pattern in the surface acoustic wave filter is coupled with the inner wiring pattern in the multilayer substrate through inductive coupling, then the attenuation characteristics outside the pass band are improved, but the distance between the electrode pattern and the multilayer substrate becomes large, resulting in insufficient coupling strength
Solution Approach 1:
The patent introduces a resin member as an intermediary component positioned between the surface acoustic wave filter and the multilayer substrate. This resin member contains a wiring pattern that serves as a intermediate coupling element, enabling strong inductive coupling with the electrode pattern while maintaining a compact overall structure. The intermediary wiring pattern in the resin member effectively bridges the gap between the filter and substrate, solving the contradiction between coupling strength and distance.
Solution Approach 2:
The patent moves the wiring pattern from the traditional substrate plane to a three-dimensional space within the resin member that covers the surface acoustic wave filter. This dimensional transition allows the wiring pattern to be positioned in optimal locations for strong coupling while maintaining a compact footprint. By utilizing the vertical dimension and spatial arrangement within the resin member, the design achieves strong coupling without increasing the horizontal distance.
2Reliability
If the distance between the electrode pattern and the multilayer substrate is reduced to improve coupling strength, then the coupling efficiency increases, but the module size cannot be reduced further
Solution Approach 1:
The patent utilizes three-dimensional spatial arrangement by positioning the wiring pattern within the resin member that covers the surface acoustic wave filter. This allows the wiring pattern to be located in optimal positions for strong coupling without increasing the horizontal footprint of the module. The vertical and lateral positioning within the resin member enables strong coupling while maintaining compact module dimensions.
Solution Approach 2:
The patent embeds the wiring pattern within the resin member structure, which itself covers the surface acoustic wave filter. This nested arrangement integrates multiple functional elements (filter, resin member, wiring pattern) into a compact hierarchy, achieving strong coupling without increasing the overall module volume. The wiring pattern is effectively nested within the resin member's three-dimensional space.
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 achieves improved attenuation characteristics outside the pass band, enabling size reduction while maintaining strong coupling, thus enhancing the performance of the surface acoustic wave filter.
Implementation Method 1
the electrode pattern and the wiring pattern are inductively coupled, capacitively coupled, or inductively coupled and capacitively coupled with each other
Implementation Method 2
the electrode pattern and the wiring pattern are inductively coupled, capacitively coupled, or inductively coupled and capacitively coupled with each other
Implementation Method 3
A surface acoustic wave filter has been widely used as a band pass filter disposed at a front end portion of a mobile communication device
Implementation Method 4
The surface acoustic wave filter is required to have a function to allow a high-frequency signal within a pass band thereof to pass therethrough with low loss and to block a high-frequency signal outside the pass band thereof with high attenuation
Data Source
AI summary
A high-frequency module includes a SAW filter including a piezoelectric substrate and an electrode pattern provided on the piezoelectric substrate, a module substrate, a resin member covering the SAW filter, and a wiring pattern connected to the electrode pattern and provided on the resin member. The electrode pattern and the wiring pattern are inductively coupled, capacitively coupled, or inductively coupled and capacitively coupled with each other.