IDT Electrode Tip-Section Structure for Low-Loss Acoustic Wave Elements
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Solution Overview
Problem
Acoustic wave elements with IDT electrodes face challenges in further improving resonance characteristics, particularly in minimizing loss.
Innovation Solution
The acoustic wave element features a piezoelectric substrate with IDT electrodes having first and second bus bars connected to different potentials, with electrode fingers and dummy electrodes arranged to intersect, and increased sections in end areas to reduce bulk wave leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the widths of the electrode fingers are increased in the vicinity of the gaps between the ends of the electrode fingers and the dummy electrodes, then the resonance characteristics are improved, but the loss is not sufficiently reduced
Solution Approach 1:
The patent applies local quality by differentiating the electrode finger structure into three distinct regions along the propagation direction: a center area with uniform width, and two end areas with increased widths. This localized modification targets specifically the regions near the gaps where bulk wave leakage occurs, while maintaining the original design in the center area where resonance performance is critical.
Solution Approach 2:
The electrode finger structure is segmented into multiple regions with different width characteristics. The center area maintains the original width for optimal resonance, while the end areas are segmented with increased widths to specifically address bulk wave leakage at the gaps between electrode fingers and dummy electrodes.
2Loss of energy
If the electrode finger widths are increased to suppress bulk wave leakage, then the loss is reduced, but the resonance characteristics may be degraded
Solution Approach 1:
The patent applies local quality by differentiating the electrode finger structure into three distinct regions along the propagation direction: a center area with uniform width, and two end areas with increased widths. This localized modification targets specifically the regions near the gaps where bulk wave leakage occurs, while maintaining the original design in the center area where resonance performance is critical.
Solution Approach 2:
The electrode finger structure is segmented into multiple regions with different width characteristics. The center area maintains the original width for optimal resonance, while the end areas are segmented with increased widths to specifically address bulk wave leakage at the gaps between electrode fingers and dummy electrodes.
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 suppresses bulk wave leakage, thereby reducing loss in the vicinity of the electrode fingers and dummy electrodes, enhancing resonance characteristics.
Implementation Method 1
an acoustic wave element using a surface acoustic wave (SAW)... a piezoelectric substrate and an IDT (interdigital transducer) provided on a major surface of the same
Implementation Method 2
The IDT electrode is for example provided with a pair of bus bars which face each other, a plurality of electrode fingers which alternately extend from one bus bar to the other bus bar side
Data Source
AI summary
In an IDT electrode of an acoustic wave element which includes first electrode fingers and second electrode fingers connected to potentials which are different from each other and arranged spaced apart from each other, the first electrode fingers includes first tip parts, and either of the first electrode fingers and the second electrode fingers includes, at a tip area extending along a direction of propagation of an acoustic wave and overlapping with the first tip parts, increase sections in which electrode volumes per unit lengths in a direction of extension of the first electrode fingers and the second electrode fingers are larger in comparison with that of the center area in which the electrode fingers intersect.