Bent IDT Electrode Layout for Unwanted Wave Suppression
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Solution Overview
Problem
Conventional acoustic wave devices fail to effectively reduce or prevent unwanted waves, particularly in the IDT electrode design where the electrode finger pitch at central portions is narrower than at end portions, leading to insufficient wave response control.
Innovation Solution
The acoustic wave device incorporates a piezoelectric substrate with an IDT electrode featuring a pair of busbars and interdigitated electrode fingers, where the electrode fingers are bent at nodes and arranged in alternating parallel and non-parallel regions, ensuring non-uniform excitation directions and varying electrode finger pitches to disperse unwanted waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the electrode finger pitch is made narrower at the central portion and wider at the end portions, then the electrode structure can be optimized for central region performance, but the response of unwanted waves is not sufficiently reduced or prevented
Solution Approach 1:
The patent applies local quality by dividing the IDT electrode into distinct regions (first region with narrower pitch, second region with wider pitch) where each region has different electrode finger pitch characteristics optimized for its specific function. This spatial variation in pitch allows the central region to maintain good electrical contact while the end regions effectively suppress unwanted waves through broader spacing.
Solution Approach 2:
The IDT electrode is segmented into multiple functional regions along the electrode finger extension direction. The first region (central portion) and second region (end portions) are clearly divided with different pitch values, creating distinct functional zones that collectively address both signal transmission and unwanted wave suppression requirements.
2Area of stationary object
If curved electrode finger shapes are used, then the electrode can cover a broader area, but the control over wave response remains insufficient
Solution Approach 1:
The patent implements local quality by varying the electrode finger pitch in different spatial regions rather than using a uniform curved design. The first region maintains narrower spacing for effective area utilization, while the second region employs wider spacing specifically targeted at suppressing unwanted waves, making the structure's response characteristics location-dependent.
Solution Approach 2:
The electrode structure employs asymmetry by creating an uneven pitch distribution across the electrode array. The transition from narrower pitch in the first region to wider pitch in the second region creates an asymmetric pattern that is optimized for directional wave control, particularly effective at suppressing unwanted waves propagating from the end regions.
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 effectively reduces or prevents unwanted waves by dispersing them across the frequency spectrum, maintaining consistent resonant and anti-resonant frequencies, thereby enhancing the resonance characteristic and reducing out-of-band noise.
Implementation Method 1
a piezoelectric substrate including a piezoelectric layer and an IDT electrode on the piezoelectric layer
Implementation Method 2
an IDT electrode on the piezoelectric layer and including a pair of busbars and a plurality of electrode fingers
Implementation Method 3
maintaining consistent resonant and anti-resonant frequencies across the intersection region, enhancing the resonance characteristic
Data Source
AI summary
An acoustic wave device includes a piezoelectric layer and an IDT electrode including first and second busbars and first and second electrode fingers. A virtual line connecting tip portions of the second electrode fingers is defined as a first envelope, and a virtual line connecting tip portions of the first electrode fingers is defined as a second envelope, and a region between the first and second envelopes is an intersection region. The intersection region includes parallel regions in which the first and second electrode fingers extend in parallel and a non-parallel region in which directions in which the first and second electrode fingers extend intersect each other. The parallel and non-parallel regions are alternately arranged in the intersection region. The first and second electrode fingers linearly extend in the parallel and non-parallel regions, and are bent at the boundaries between the parallel and non-parallel regions.