Acoustic Wave Filter Conductor Layout for Low-Profile Isolation
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Solution Overview
Problem
Existing acoustic wave devices face challenges in achieving both improved isolation characteristics and a low profile, as the ground electrode, insulating film, and signal electrode laminations hinder this balance.
Innovation Solution
The acoustic wave device incorporates a first conductor portion interposed between two acoustic wave filters, with the ground electrode overlapping the first functional conductor portion but not the signal electrode, and additional conductor portions spaced apart from the main surface to reduce parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ground electrode, insulating film, and signal electrode are laminated on the second main surface of the first piezoelectric substrate, then isolation characteristics between the first functional electrode and signal electrode are improved, but the device profile increases
Solution Approach 1:
The patent transitions from a two-dimensional lamination approach (stacking ground electrode, insulating film, and signal electrode on the same surface) to a three-dimensional spatial arrangement where the ground electrode is positioned at a different height level. Specifically, the ground electrode is placed on the second main surface of the first piezoelectric substrate while the signal electrode is positioned on the first main surface, utilizing the thickness dimension to achieve both isolation and compactness.
Solution Approach 2:
The patent introduces an insulating film as an intermediary element between the ground electrode and signal electrode. This insulating film is positioned between the two electrodes in the thickness direction, providing electrical isolation without requiring the electrodes to be laminated on the same surface, thus maintaining a low profile while achieving good isolation characteristics.
2Device complexity
If the second conductor portion is positioned close to the first main surface, then device integration is improved, but parasitic capacitance between the first functional conductor portion and second conductor portion increases
Solution Approach 1:
The patent applies local quality by creating different spatial zones with different electrical characteristics. The second conductor portion is positioned in a specific local region between the first main and second main surfaces, spaced apart from the first main surface to minimize parasitic capacitance in that local area, while still maintaining overall device integration through strategic positioning.
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 enhances isolation characteristics and maintains a low profile, improving filter performance by reducing capacitive coupling and parasitic capacitance between the functional conductor portions.
Implementation Method 1
The first piezoelectric substrate includes a first main surface and a second main surface that face away from each other. The first functional conductor portion is provided on the first main surface of the first piezoelectric substrate.
Data Source
AI summary
An acoustic wave device includes a first acoustic wave filter, a first conductor portion between the first acoustic wave filter and a second acoustic wave filter and connected to a second functional conductor portion of the second acoustic wave filter. The first acoustic wave filter includes a signal electrode on a second main surface of a first piezoelectric substrate and connected to the first conductor portion, a ground electrode on the second main surface of the first piezoelectric substrate, and a second conductor portion connected to the ground electrode. The ground electrode overlaps a first functional conductor portion and does not overlap the signal electrode in a thickness direction of the first piezoelectric substrate. The second conductor portion is located between first and second main surfaces of the first piezoelectric substrate and spaced apart from the first main surface.