SAW Resonator Gap Grating Structure for Transversal Mode Suppression
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Solution Overview
Problem
Surface acoustic wave (SAW) electroacoustic devices face challenges in reducing transversal acoustic wave modes, which lead to undesirable ripples in the filter passband and performance degradation due to the generation of spurious acoustic wave modes.
Innovation Solution
The introduction of a gap grating structure with a specific pitch between busbars and electrode fingers in the electrode structure of SAW resonators, which controls acoustic velocities in different regions to suppress transversal acoustic wave modes, thereby enhancing the filter's performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional interdigitated transducer structure is used, then the device is simple in structure, but transversal acoustic wave modes are generated causing ripples in the filter passband
Solution Approach 1:
The transducer is divided into multiple segments: a first interdigitated transducer with first electrode fingers, a second interdigitated transducer with second electrode fingers, and additional conductive structures. Each segment serves a specific function in controlling acoustic wave modes, allowing the overall structure to suppress transversal modes while maintaining manageable complexity through modular design
Solution Approach 2:
Different regions of the electrode structure are designed with different properties: the first and second interdigitated transducers have specific pitch relationships to each other, and additional conductive structures are placed at specific locations with specific pitches. This local differentiation allows targeted suppression of transversal acoustic modes in specific regions without affecting the entire structure uniformly
2Reliability
If the pitch of electrode fingers is reduced to suppress transversal modes, then filter performance improves, but manufacturing precision requirements increase
Solution Approach 1:
The invention specifies particular pitch relationships between different transducer segments (e.g., the pitch of the second interdigitated transducer is different from the first, and additional conductive structures have pitches that are multiples or fractions of the first pitch). These parameter relationships provide a systematic approach to controlling acoustic modes while maintaining manufacturability through defined geometric progressions rather than arbitrary precision requirements
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 transversal acoustic wave modes, leading to improved filter performance with reduced ripples in the passband and increased efficiency in wireless communication devices.
Implementation Method 1
Using a piezoelectric material as a vibrating medium, acoustic resonators operate by transforming an electrical signal wave that is propagating along an electrical conductor into an acoustic wave that is propagating via the piezoelectric material.
Implementation Method 2
Surface acoustic wave (SAW) electroacoustic devices face challenges in reducing transversal acoustic wave modes
Data Source
AI summary
Aspects of the disclosure relate to an electroacoustic device that includes a piezoelectric material and an electrode structure. The electrode structure includes a first busbar and a second busbar. The electrode structure further includes a first conductive structure connected to the first busbar and a second conductive structure connected to the second busbar. The first conductive structure and the second conductive structure is disposed between the first busbar and the second busbar. The first conductive structure and the second conductive structure each include a plurality of conductive segments separated from each other and extending towards one of the first busbar or the second busbar. The electrode structure further includes electrode fingers arranged in an interdigitated manner and each connected to either the first conductive structure or the second conductive structure. The electrode fingers have a pitch that is different than a pitch of the plurality of conductive segments.