Acoustic Wave Resonator Structure With Hollow Support for Size Reduction
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Solution Overview
Problem
Existing acoustic wave devices are limited by their size due to the need for large resonators to achieve high capacitance, which increases the device's overall dimensions.
Innovation Solution
The acoustic wave device incorporates multiple resonators with a support structure that includes a hollow portion, a piezoelectric layer with specific cut-angles, and functional electrodes arranged to match the hollow portion, allowing for efficient excitation of bulk waves and reducing device size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If large resonators are used to achieve high capacitance, then the capacitance increases, but the device size increases
Solution Approach 1:
The patent divides the resonator structure into multiple segments including a support substrate, piezoelectric layer, and functional electrodes. This segmentation allows for optimized capacitance in each layer while maintaining compact overall dimensions, resolving the contradiction between high capacitance and small size
Solution Approach 2:
The patent utilizes the thickness dimension of the piezoelectric layer to increase capacitance without expanding the planar area. By optimizing the piezoelectric layer thickness and electrode configuration in the vertical dimension, high capacitance is achieved while keeping the device footprint small
2Device complexity
If the number of electrode pairs is reduced, then the device complexity decreases, but the resonance characteristics and coupling factors deteriorate
Solution Approach 1:
The patent changes the parameters of existing electrode pairs to improve their efficiency. By optimizing the electrode width, spacing, and positioning relative to the hollow portion, each electrode pair generates stronger electric fields and achieves better resonance characteristics without increasing the number of pairs
Solution Approach 2:
The patent employs composite material structures including the piezoelectric layer combined with functional electrodes and the support substrate with hollow portions. This composite structure enhances the coupling factor and resonance characteristics by leveraging the synergistic effects of different materials and geometries
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 reduces the size of acoustic wave devices while maintaining high resonance characteristics and coupling factors, even when the number of electrode pairs is minimized.
Implementation Method 1
a piezoelectric layer, and a functional electrode... The piezoelectric layer is provided on one main surface of the support... The functional electrode is provided on at least one of the first and second main surfaces of the piezoelectric layer
Data Source
AI summary
An acoustic wave device includes resonators including a support with a hollow portion, a piezoelectric layer, and a functional electrode. The piezoelectric layer is on one main surface of the support and includes first and second main surfaces. The functional electrode is on at least one main surface of the piezoelectric layer and partially matches the hollow portion as seen in a thickness direction of the piezoelectric layer. The resonators include first and second resonators. The functional electrode of the first resonator includes at least one pair of a first and second electrode on the same main surface of the piezoelectric layer. The functional electrode of the second resonator includes upper and lower surface electrodes on the first and second main surfaces of the piezoelectric layer.