Curved Acoustic Resonator Layout for Lower Coupling Loss
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Solution Overview
Problem
Acoustic coupling between acoustic wave resonators with curved electrode fingers leads to degradation of electrical characteristics, such as increased insertion loss and spurious wave generation.
Innovation Solution
The acoustic wave device incorporates a configuration where at least one resonator electrode is curved, with specific positioning and dimensions to minimize acoustic coupling by ensuring resonators face each other on their outer sides, and includes a scattering pattern to further reduce interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If curved electrode fingers are used in acoustic wave resonators, then spurious waves are suppressed, but acoustic coupling between resonators increases causing degradation of electrical characteristics
Solution Approach 1:
The patent positions resonator electrodes asymmetrically relative to the curved electrode fingers. Specifically, resonator electrodes are positioned on the convex side of the curved electrode fingers rather than symmetrically, which prevents acoustic wave leakage toward adjacent resonators while maintaining the spurious wave suppression benefit of curved electrodes
2Area of stationary object
If resonator electrodes are positioned close to each other, then device area is reduced, but acoustic coupling occurs causing increased insertion loss
Solution Approach 1:
The patent introduces a specific geometric configuration as an intermediary solution: positioning resonator electrodes on the convex side of curved electrode fingers. This configuration acts as a spatial mediator that allows resonators to be closely spaced while the convex geometry redirects acoustic waves away from adjacent resonators, preventing energy loss through acoustic coupling
3Stability of the object's composition
If curved resonator electrodes are used, then acoustic wave confinement is improved, but acoustic leakage toward adjacent resonators occurs
Solution Approach 1:
The patent applies local quality by differentiating the positioning strategy for different parts of the resonator structure. The resonator electrodes are positioned on the convex side of the curved electrode fingers, creating a localized geometric feature that redirects acoustic waves in a specific direction, thereby maintaining confinement within the intended resonator while preventing leakage toward adjacent structures
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 acoustic coupling and prevents degradation of electrical characteristics, minimizing spurious waves and improving return loss.
Implementation Method 1
a piezoelectric substrate including a piezoelectric layer
Implementation Method 2
Each of the plurality of resonator electrodes includes an interdigital transducer (IDT) electrode
Data Source
AI summary
An acoustic wave device includes a piezoelectric substrate including a piezoelectric layer, and resonator electrodes on the piezoelectric substrate and each including electrode fingers and an IDT electrode. The resonator electrodes include first and second resonator electrodes. At least one of the first and second resonator electrodes includes a curved resonator electrode in which the electrode fingers have a curved shape in plan view. The first and second resonator electrodes face each other, and a resonator electrode is positioned on a convex side, in a direction in which the electrode fingers are arranged, of a portion including the curved shape of the curved resonator electrode.