Acoustic Wave Electrode Layout for Transverse Mode Suppression
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Solution Overview
Problem
Existing acoustic wave devices struggle to sufficiently suppress transverse modes, leading to higher loss and spurious responses, which are not adequately addressed by current technologies.
Innovation Solution
The acoustic wave device incorporates a piezoelectric substrate with a convex reverse-velocity surface and an IDT electrode featuring recesses in the edge regions, along with a specific layer structure including high- and low-acoustic-velocity films, to create a piston mode that reduces transverse modes by varying acoustic velocities across different regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If mass-adding films are provided in the inner edge regions or electrode finger width is increased to reduce acoustic velocity, then transverse modes are suppressed, but loss and spurious responses are not sufficiently reduced
Solution Approach 1:
The patent applies local quality by providing recesses only in the inner edge regions of the piezoelectric substrate, while maintaining the central excitation region without recesses. This creates localized acoustic velocity variations that suppress transverse modes without affecting the central region's acoustic properties, thereby reducing transverse modes while minimizing impact on energy loss
Solution Approach 2:
The patent segments the piezoelectric substrate into distinct regions: a central excitation region without recesses and inner edge regions with recesses. This segmentation allows independent optimization of each region's acoustic properties, enabling transverse mode suppression in edge regions while preserving central region performance for minimal energy loss
2Object-affected harmful factors
If mass-adding films are provided in the inner edge regions or electrode finger width is increased to reduce acoustic velocity, then transverse modes are suppressed, but spurious responses are not sufficiently reduced
Solution Approach 1:
The patent applies local quality by providing recesses only in the inner edge regions of the piezoelectric substrate, while maintaining the central excitation region without recesses. This creates localized acoustic velocity variations that suppress transverse modes without affecting the central region's acoustic properties, thereby reducing transverse modes while minimizing impact on energy loss
Solution Approach 2:
The patent segments the piezoelectric substrate into distinct regions: a central excitation region without recesses and inner edge regions with recesses. This segmentation allows independent optimization of each region's acoustic properties, enabling transverse mode suppression in edge regions while preserving central region performance for minimal energy loss
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 significantly reduces or prevents transverse modes, resulting in improved impedance-frequency characteristics and reduced spurious responses, enhancing the performance of acoustic wave devices by minimizing ripple generation and increasing productivity during manufacturing.
Implementation Method 1
a piezoelectric substrate in which a reverse-velocity surface is convex and an IDT electrode provided on the piezoelectric substrate
Implementation Method 2
an IDT electrode provided on the piezoelectric substrate. The IDT electrode includes a first busbar and a second busbar that face each other, a plurality of first electrode fingers including first ends that are connected to the first busbar
Data Source
AI summary
An acoustic wave device includes a piezoelectric substrate in which a reverse-velocity surface is convex and an IDT electrode on the piezoelectric substrate. When an acoustic wave propagation direction is a first direction and a direction perpendicular or substantially perpendicular to the first direction is a second direction, the portion of the IDT electrode where first and second electrode fingers overlap in the first direction is a crossing region. The crossing region includes a center region centrally located in the second direction and a first and second edge regions located on two sides of the center region. Recesses 17 and 18 are respectively provided in portions of the piezoelectric substrate located in the first and second edge regions between the portions where the first and second electrode fingers are provided.