Acoustic Wave Filter Substrate Layout for Better Signal Isolation
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Solution Overview
Problem
Existing acoustic wave devices face challenges in improving isolation characteristics when mounted on substrates with large ground electrodes, leading to signal leakage and reduced impedance.
Innovation Solution
The acoustic wave device incorporates a multilayer mounting substrate with a ground electrode that includes a missing portion over the inter-wiring-line region, enhancing signal isolation by increasing path impedance and reducing signal leakage between signal wiring lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ground electrode area is made large to reduce impedance, then the ground electrode impedance is reduced, but the isolation characteristics deteriorate due to signal leakage between signal wiring lines
Solution Approach 1:
The ground electrode is segmented into multiple separate ground electrodes positioned at different locations. This segmentation prevents signal leakage paths between signal wiring lines by breaking the continuous ground potential, thereby improving isolation characteristics while maintaining effective grounding.
Solution Approach 2:
Ground electrodes are strategically positioned to provide local grounding functionality rather than using a single large continuous ground electrode. This allows different regions of the substrate to have different grounding characteristics optimized for their specific functions, reducing signal leakage while maintaining overall ground effectiveness.
2Reliability
If a large area ground electrode is used to reduce impedance, then the ground electrode impedance is reduced, but the isolation characteristics cannot be sufficiently improved
Solution Approach 1:
The ground electrode is divided into multiple separate ground electrodes positioned at different locations. This segmentation prevents signal leakage paths between signal wiring lines by breaking the continuous ground potential, thereby improving isolation characteristics while maintaining effective grounding.
Solution Approach 2:
Multiple ground electrodes act as intermediary grounding points distributed across the substrate. These intermediary ground points provide localized reference potentials that prevent signal leakage between signal lines without requiring a single large continuous ground electrode.
Data Source
AI summary
An acoustic wave device includes a mounting substrate including a multilayer body that includes a first layer including first and second signal wiring lines at least partially facing each other, and a second layer including a ground electrode, and an acoustic wave filter on the mounting substrate and electrically connected to the first signal wiring line, the second signal wiring line, and the ground electrode. The ground electrode overlaps the first and second signal wiring lines, and a region between the first and second signal wiring lines in plan view. A portion of the second layer overlapping the inter-wiring-line region in plan view includes a ground electrode missing portion.