Acoustic Wave Electrode Layout for Transverse Mode Suppression
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Solution Overview
Problem
Existing acoustic wave devices struggle to sufficiently inhibit the transverse mode due to manufacturing variations in the shape of inner edge regions and mass addition films, which affect acoustic velocity differentiation.
Innovation Solution
An acoustic wave device with a piezoelectric substrate having a convex reverse-velocity surface, an interdigital transducer electrode with specific busbar and electrode finger configurations, and mass addition films stacked in strategic regions to reduce acoustic velocity variations and promote a piston mode, thereby effectively reducing or preventing transverse modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mass addition films are disposed only in inner edge regions with increased electrode finger width, then acoustic velocity differentiation is achieved, but manufacturing variations in shape and position prevent sufficient acoustic velocity reduction, leading to inadequate transverse mode inhibition
Solution Approach 1:
The patent applies local quality by differentiating the electrode structure into multiple regions (central excitation region, inner edge regions, outer edge regions) with distinct characteristics. Each region has specifically designed electrode finger widths and mass addition film configurations to create localized acoustic velocity variations, ensuring robust transverse mode suppression despite manufacturing tolerances
Solution Approach 2:
The patent changes physical parameters by varying electrode finger widths across different regions and controlling mass addition film thicknesses. The central excitation region has a first electrode finger width, inner edge regions have increased second electrode finger widths, and outer edge regions have third electrode finger widths, creating a gradient structure that ensures sufficient acoustic velocity differentiation
2Reliability
If the acoustic velocity in inner edge regions is not sufficiently reduced due to manufacturing variations, then the acoustic velocities in different regions cannot be sufficiently differentiated, but increasing the mass addition film thickness or area may introduce other device complexity or manufacturing difficulty
Solution Approach 1:
The patent segments the electrode structure into distinct regions (central excitation region, inner edge regions, outer edge regions) with different electrode finger widths and mass addition film configurations. This segmentation allows independent optimization of each region's acoustic velocity characteristics without requiring complex overall redesign
Solution Approach 2:
The patent applies partial action by selectively increasing electrode finger widths only in inner edge regions and applying mass addition films specifically in those regions, rather than uniformly across the entire electrode. This targeted approach achieves sufficient acoustic velocity differentiation with minimal added complexity
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 device achieves more certain reduction or prevention of transverse modes by controlling acoustic velocities through the piston mode, even with manufacturing variations, and improves electromechanical coupling coefficients and return loss.
Implementation Method 1
piezoelectric substrate
Data Source
AI summary
An acoustic wave device includes a piezoelectric substrate a reverse-velocity surface of which is convex, an interdigital transducer electrode disposed on the piezoelectric substrate, and mass addition films stacked above the interdigital transducer electrode. The interdigital transducer electrode includes a central region, first and second edge regions, first and second gap regions located outside the first and second edge regions, first and second inner busbar regions, and first and second outer busbar regions. The mass addition films are stacked in at least the first and second edge regions and the first and second inner busbar regions.