Acoustic Wave Filter Layout With Slit Diffraction Coupling Suppression
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Solution Overview
Problem
Acoustic coupling between adjacent acoustic wave elements on a piezoelectric substrate leads to ripple in the pass band of acoustic wave filters, making it difficult to achieve both compactness and sufficient suppression of coupling, as existing solutions like diffraction patterns and absorbers are ineffective in minimizing dimensions without compromising coupling suppression.
Innovation Solution
Incorporating a diffracting component with a slit in the overlap region of intersecting IDT electrodes, which diffracts acoustic waves orthogonally to the propagation direction, reducing coupling between adjacent acoustic wave elements while allowing for miniaturization without increasing the dimension of the diffraction component.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a diffraction pattern or absorber is disposed between IDT electrodes to suppress acoustic coupling, then acoustic coupling is reduced, but the spacing between acoustic wave elements increases
Solution Approach 1:
The diffracting component utilizes diffraction in a direction orthogonal to the acoustic wave propagation direction to suppress coupling. By diffracting acoustic waves sideways rather than requiring longitudinal spacing, the solution addresses acoustic coupling suppression without increasing the spacing between acoustic wave elements in the propagation direction, thus resolving the contradiction between coupling suppression and device compactness
2Length of stationary object
If the dimension of diffraction pattern or absorber is reduced to achieve miniaturization, then device size is reduced, but acoustic coupling suppression becomes insufficient
Solution Approach 1:
The diffracting component exploits diffraction in the orthogonal direction (perpendicular to propagation) rather than requiring large dimensions in the propagation direction. This dimensional shift allows effective coupling suppression with a compact structure that does not compromise device miniaturization while maintaining sufficient acoustic coupling suppression
3Productivity
If acoustic waves propagate through one acoustic wave element, then signal transmission is achieved, but acoustic waves may enter the IDT electrode of adjacent acoustic wave elements causing coupling
Solution Approach 1:
The diffracting component acts as an intermediary element disposed between adjacent IDT electrodes. It intercepts and diffracts acoustic waves that have propagated through one acoustic wave element, preventing them from entering the IDT electrode of adjacent elements. This mediator approach allows signal transmission through individual elements while blocking cross-element coupling
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
Effectively reduces or prevents acoustic coupling between adjacent acoustic wave elements, minimizing ripple in the pass band and enabling further miniaturization of acoustic wave devices without compromising coupling suppression.
Implementation Method 1
a diffracting component including a slit is provided in the overlap region... which diffracts acoustic waves orthogonally to the propagation direction
Data Source
AI summary
An acoustic wave device includes first and second acoustic wave elements. The first acoustic wave element is disposed on a piezoelectric substrate, and includes at least one first IDT electrode. The second acoustic wave element is disposed on the piezoelectric substrate, and includes at least one second IDT electrode. The first and second acoustic wave elements are adjacent to each other in the direction of acoustic wave propagation. A diffracting component that diffracts an acoustic wave is disposed between the first IDT electrode and the second IDT electrode. The diffracting component includes a gap that defines and functions as a slit to diffract an acoustic wave.