IDT Resonator Velocity Zoning for Acoustic Ripple Suppression
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Solution Overview
Problem
Existing acoustic wave devices with IDT electrodes face challenges in suppressing ripples of unwanted waves in resonance characteristics, which affect the performance and accuracy of resonators.
Innovation Solution
The acoustic wave device incorporates a piezoelectric substrate with an IDT electrode design featuring specific busbar and electrode finger configurations, including varying thickness and width regions, which modulate acoustic wave velocities across different regions to suppress unwanted wave ripples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If wide portions are provided at the front ends of electrode fingers to improve acoustic wave velocity distribution, then unwanted wave ripple is partially suppressed, but further ripple suppression is insufficient
Solution Approach 1:
The patent applies local quality by creating distinct regions (first, second, third, and fourth regions) with different acoustic wave velocities at specific locations within the electrode finger structure. Each region is positioned to control wave propagation locally, with the first and second regions having higher velocities than the third and fourth regions, thereby achieving comprehensive ripple suppression through localized velocity modulation rather than uniform design
Solution Approach 2:
The electrode finger structure is segmented into multiple functional regions along the acoustic wave propagation direction. The first and second regions (with higher acoustic wave velocities) are positioned at specific locations, while the third and fourth regions (with lower velocities) are positioned elsewhere, creating a segmented velocity profile that systematically controls wave propagation and suppresses unwanted waves throughout the entire structure
2Object-affected harmful factors
If uniform electrode finger design is used, then manufacturing is simple, but acoustic wave velocity distribution is insufficient to suppress unwanted waves
Solution Approach 1:
Rather than making the entire electrode structure complex, the patent applies local quality by introducing velocity-differentiating features only in specific regions (first, second, third, and fourth regions) while maintaining simpler structures elsewhere. This localized approach achieves the necessary acoustic wave velocity distribution for ripple suppression without uniformly increasing device complexity across the entire electrode assembly
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 design effectively reduces unwanted wave ripples by creating regions with distinct acoustic wave velocities, enhancing the resonance characteristics and mode distribution, thereby improving the device's performance.
Implementation Method 1
a piezoelectric substrate, and an IDT electrode on the piezoelectric substrate
Implementation Method 2
an acoustic wave velocity in the first gap region and an acoustic wave velocity in the second gap region are higher than an acoustic wave velocity in a middle region
Data Source
AI summary
In an acoustic wave device, a resonator including an IDT electrode and a portion of a piezoelectric substrate includes a middle region, a first gap region, a second gap region, a first edge region, a second edge region, a first intermediate region, and a second intermediate region. The first intermediate region is located between the middle region and the first edge region. The second intermediate region is located between the middle region and the second edge region. An acoustic wave velocity in the first intermediate region and in the second intermediate region are lower than an acoustic wave velocity in the middle region and higher than an acoustic wave velocity in the first edge region and an acoustic wave velocity in the second edge region.