Rotated IDT Electrode Geometry for SAW Transverse Mode Control
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Solution Overview
Problem
Surface acoustic wave (SAW) resonators with multi-layer piezoelectric substrates experience transverse modes, which hinder their figure of merit and lead to reduced performance in filtering radio frequency signals.
Innovation Solution
The introduction of an interdigital transducer electrode with a non-zero rotation angle and tilt angle, ranging from 2° to 14°, helps suppress transverse modes and enhance the figure of merit of SAW resonators by optimizing the configuration of the electrode's orientation relative to the wave propagation direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an interdigital transducer electrode with non-zero rotation angle and tilt angle is introduced, then the figure of merit and quality factor are improved, but the device complexity increases
Solution Approach 1:
The patent applies parameter changes by optimizing the rotation angle (α) and tilt angle (β) of the interdigital transducer electrode. Specific angle ranges are defined: rotation angle α between 0°-30° and tilt angle β between 0°-45°, with preferred ranges of α between 10°-20° and β between 20°-30°. These parameter optimizations suppress transverse modes and enhance the figure of merit from conventional values below 100 to above 140, resolving the contradiction between improved reliability and increased device complexity.
2Reliability
If the interdigital transducer electrode is rotated and tilted to suppress transverse modes, then the quality factor increases, but the manufacturing precision requirements increase
Solution Approach 1:
The patent defines specific parameter ranges for rotation angle (α: 0°-30°, preferably 10°-20°) and tilt angle (β: 0°-45°, preferably 20°-30°) that balance manufacturing feasibility with performance optimization. These parameter specifications enable manufacturers to achieve the desired quality factor improvement (FOM > 140) while maintaining practical manufacturing precision requirements, rather than requiring extremely precise angle control.
3Stability of the object's composition
If the interdigital transducer electrode configuration is optimized with rotation and tilt angles, then passband ripples are reduced, but the device complexity increases
Solution Approach 1:
The patent utilizes parameter changes by optimizing the rotation angle (α) and tilt angle (β) of the interdigital transducer electrode to suppress transverse modes and reduce passband ripples. The specified angle ranges (α: 0°-30°, β: 0°-45°) achieve improved passband stability with minimal increase in device complexity, as the electrode structure remains fundamentally the same interdigital design, only with modified orientation parameters.
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 improves the quality factor, electromechanical coupling coefficient, and figure of merit of SAW resonators, leading to more effective filtering of radio frequency signals and reduced passband ripples.
Implementation Method 1
A surface acoustic wave resonator can include an interdigital transductor electrode on a piezoelectric substrate. The surface acoustic wave resonator can generate a surface acoustic wave on a surface of the piezoelectric layer on which the interdigital transductor electrode is disposed.
Implementation Method 2
The surface acoustic wave resonator can generate a surface acoustic wave on a surface of the piezoelectric layer on which the interdigital transductor electrode is disposed.
Data Source
AI summary
Acoustic wave resonators are disclosed that include a piezoelectric layer and an interdigital transducer electrode over the piezoelectric layer. The interdigital transducer electrode has a rotation angle and a tilt angle. The rotation angle and the tilt angle can together increase a figure of merit of the acoustic wave device. The rotation angle and the tilt angle can both be non-zero.