Stacked Acoustic Wave Filter Layout With Shielded Isolation
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Solution Overview
Problem
The existing acoustic wave devices face deterioration in isolation characteristics due to interference between stacked acoustic wave filters, which hampers their downsizing potential.
Innovation Solution
An acoustic wave device design featuring a first substrate with a first acoustic wave filter and a second substrate flip-chip mounted on it, with a shield electrode positioned between the filters through an air gap to inhibit interference, enhancing isolation characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If acoustic wave filters are stacked on different surfaces to downsize the device, then device height is reduced, but isolation characteristics deteriorate due to interference between filters
Solution Approach 1:
A shield electrode is introduced as an intermediary element between the first acoustic wave filter on the upper surface and the second acoustic wave filter on the lower surface. The shield electrode, supported by the upper surface and positioned through the air gap, acts as a mediator to block electromagnetic interference between the stacked filters, thereby maintaining isolation characteristics while enabling device downsizing through stacking.
2Device complexity
If acoustic wave filters are stacked face-to-face across an air gap, then device complexity is reduced, but harmful electromagnetic interference increases between filters
Solution Approach 1:
The shield electrode serves as a mediator inserted between the two stacked acoustic wave filters. It blocks the electromagnetic fields generated by each filter from interfering with the other, thereby eliminating the harmful electromagnetic interference that would otherwise result from the simplified face-to-face stacking configuration.
3Reliability
If a shield electrode is added between stacked filters, then isolation characteristics improve, but device complexity increases
Solution Approach 1:
The shield electrode is designed to perform multiple functions: it provides electromagnetic shielding between the stacked filters to improve isolation characteristics, while also being supported by the existing upper surface structure. This multi-functional design minimizes the additional complexity introduced by the shield electrode, as it leverages existing structural elements rather than requiring completely new support mechanisms.
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
The implementation of the shield electrode between the acoustic wave filters improves isolation characteristics, preventing signal leakage and allowing for the reduction in device height while maintaining effective filter functionality.
Implementation Method 1
a shield electrode that is supported by the upper surface of the first substrate, and is located between at least a part of the first acoustic wave filter and at least a part of the second acoustic wave filter through the air gap
Data Source
AI summary
An acoustic wave device includes: a first substrate that includes a first acoustic wave filter located on an upper surface of the first substrate; a second substrate that is flip-chip mounted on the upper surface of the first substrate through a bump, and includes a second acoustic wave filter on a lower surface of the second substrate, the lower surface of the second substrate facing the upper surface of the first substrate across an air gap; and a shield electrode that is supported by the upper surface of the first substrate, and is located between at least a part of the first acoustic wave filter and at least a part of the second acoustic wave filter through the air gap.