Acoustic Wave Electrode Layout With Local Width Variation
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Solution Overview
Problem
End surface reflection acoustic wave devices suffer from energy leakage at the intersecting portion of electrode fingers, leading to deteriorated resonance characteristics.
Innovation Solution
Incorporating different width portions on the piezoelectric body, specifically thin or thick width portions at the intersecting region, and using a support member with high or low acoustic velocity materials to confine acoustic wave energy, reducing leakage and enhancing resonance characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If electrode fingers are arranged parallel to each other on a piezoelectric body, then the device structure is simple and easy to manufacture, but acoustic wave energy leaks to the outer side portion causing deteriorated resonance characteristics
Solution Approach 1:
The patent applies local quality by introducing a different width portion at the central part of the intersecting region between electrode fingers. This local structural variation creates a low acoustic velocity region that confines acoustic wave energy, preventing leakage to outer portions while maintaining the overall simple parallel electrode structure for ease of manufacture.
Solution Approach 2:
The patent changes the width parameter of the piezoelectric body at the central part of the intersecting region to create a different width portion. This parameter change (reducing width locally) creates a low acoustic velocity region that improves resonance characteristics by confining acoustic wave energy, while the rest of the structure maintains its original simple geometry.
2Device complexity
If the piezoelectric body has uniform width, then the manufacturing process is simple, but acoustic wave energy leaks at the intersecting portion of electrode fingers
Solution Approach 1:
The patent introduces a local structural variation (different width portion) at the central part of the intersecting region while keeping the rest of the piezoelectric body with uniform width. This localized modification creates a low acoustic velocity region that confines acoustic wave energy, preventing leakage without significantly increasing overall device complexity.
Solution Approach 2:
The patent segments the piezoelectric body width into two distinct regions: a main uniform width region and a local different width portion at the central part of the intersecting region. This segmentation allows the device to maintain simple uniform geometry most places while introducing targeted structural variation where needed to prevent energy leakage.
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 solution effectively reduces energy leakage and improves resonance characteristics by creating regions of varying acoustic velocities, resulting in improved performance of acoustic wave devices, high-frequency front end circuits, and communication apparatuses.
Implementation Method 1
a piezoelectric body including the first end surface and the second end surface, and a first principal surface and a second principal surface opposing each other and connecting the first end surface and the second end surface
Implementation Method 2
an end surface reflection acoustic wave device in which acoustic waves are reflected between a first end surface and a second end surface opposing each other
Implementation Method 3
the piezoelectric body is provided with a different width portion having a width different from the width of the piezoelectric body at a central portion of the intersecting portion in the second direction
Data Source
AI summary
An acoustic wave device includes first and second electrode fingers provided on a first principal surface of a piezoelectric body. In a case that a portion where the first electrode finger and the second electrode finger overlap with each other when they are viewed from a first direction connecting the first and second end surfaces is an intersecting portion, and a distance between the first end surface and the second end surface in the piezoelectric body is a width of the piezoelectric body, a different width portion having a width different from the width of the piezoelectric body at a central portion of the intersecting portion in a second direction is provided in a region where the first end surface and the second end surface oppose each other.