Acoustic Wave Resonator Layout for Compact Ripple-Suppressed Filters
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Solution Overview
Problem
Existing acoustic wave filter devices face challenges in reducing size while maintaining effective performance, particularly in achieving both characteristics and size reduction.
Innovation Solution
The acoustic wave filter device incorporates a plurality of acoustic wave resonators with a specific configuration, including a piezoelectric substrate and an IDT electrode with a central region and surrounding regions of varying acoustic velocities, optimized to reduce size while preventing transverse mode ripple and maintaining filter characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the acoustic wave filter device uses a conventional IDT electrode configuration, then the device can maintain standard filter characteristics, but the device size cannot be reduced
Solution Approach 1:
The patent applies local quality by creating distinct acoustic velocity regions (first, second, and third regions with different acoustic velocities) within the IDT electrode structure. Each region is designed with specific acoustic velocity characteristics to control wave propagation locally, enabling size reduction while maintaining overall filter performance through localized acoustic property optimization.
2Volume of moving object
If the acoustic wave filter device reduces size, then the device becomes more compact, but transverse mode ripple increases
Solution Approach 1:
The patent employs parameter changes by systematically varying the acoustic velocity parameters across different regions of the IDT electrode. The first, second, and third regions are designed with progressively different acoustic velocities, creating a controlled gradient that manages wave propagation and suppresses transverse mode ripple while enabling compact device dimensions.
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 achieves both size reduction and improved filter performance by optimizing the acoustic wave resonators' structure, reducing transverse mode ripple and maintaining effective filter characteristics.
Implementation Method 1
Each of the plurality of acoustic wave resonators includes a piezoelectric substrate and an IDT electrode. The IDT electrode is provided on the piezoelectric substrate.
Implementation Method 2
a wavelength of an acoustic wave determined by an electrode finger pitch of the IDT electrode is defined as A
Data Source
AI summary
In a plan view in a thickness direction of a piezoelectric substrate, each of acoustic wave resonators includes a central region, a first region having a lower acoustic wave velocity than that of the central region, and a second region having a lower acoustic wave velocity than that of the central region. A first acoustic wave resonator includes a third region having a gap of about 0.3λ or longer in a predetermined direction outside of the first region and having a higher acoustic velocity of the acoustic wave than that of the central region, and a fourth region having a gap of about 0.3λ or longer in the predetermined direction outside of the second region and having a higher acoustic velocity of the acoustic wave than that of the central region. A second acoustic wave resonator does not include the third and fourth regions.