Rotated and Tilted IDT Layout for SAW Transverse Mode Suppression
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Solution Overview
Problem
Certain surface acoustic wave (SAW) resonators experience transverse modes, which hinder accuracy and stability by creating passband ripples and limiting rejection, leading to a figure of merit (FOM) that is less than desired.
Innovation Solution
Implementing an interdigital transducer (IDT) electrode with a combination of rotation and tilt angles, where the sum of these angles ranges from 2° to 14°, to suppress transverse modes and enhance the FOM of SAW resonators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional interdigital transducer electrode configuration is used, then device simplicity is maintained, but transverse modes are not suppressed and figure of merit remains low
Solution Approach 1:
The patent applies parameter changes by introducing specific rotation and tilt angles to the interdigital transducer electrode. The rotation angle ranges from 1° to 15° and the tilt angle ranges from 5° to 20°, which are deliberate parameter modifications to the electrode geometry. These angular parameter changes suppress transverse modes and increase the figure of merit above 140, resolving the contradiction between maintaining simplicity and improving performance.
2Manufacturing precision
If standard electrode orientation is used, then manufacturing is straightforward, but transverse modes create passband ripples and limit rejection
Solution Approach 1:
The patent implements asymmetry by rotating and tilting the interdigital transducer electrode away from the conventional symmetric orientation. The electrode is rotated by 1° to 15° and tilted by 5° to 20° relative to the standard configuration. This asymmetric positioning suppresses transverse modes and eliminates passband ripples, achieving high manufacturing precision for mode suppression while the angles remain small enough to maintain ease of fabrication.
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 combination of rotation and tilt angles in the IDT electrode effectively suppresses transverse modes, resulting in improved FOM values above 140, enhancing the performance and stability of SAW resonators.
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 rotation angle and the tilt angle are together configured to cause an increase in a figure of merit of the acoustic wave resonator relative to a configuration having a zero rotation angle and a zero tilt angle. The rotation angle and the tilt angle are together configured to cause a transverse mode to be suppressed.
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.