Comb Electrode Structure for Compact Acoustic Wave Filters
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Solution Overview
Problem
High-frequency acoustic wave devices, such as those used in communication systems, face challenges in reducing size while maintaining electrostatic capacitance and impedance characteristics, which affects their performance and efficiency.
Innovation Solution
The design incorporates a pair of comb-shaped electrodes with protrusion and recessed portions on their side surfaces, arranged randomly in the extension direction, to increase electrostatic capacitance, allowing for a reduction in device size while maintaining the same electrostatic capacitance and impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the device size is reduced, then the compactness is improved, but the electrostatic capacitance decreases
Solution Approach 1:
The invention transitions from a two-dimensional flat electrode structure to a three-dimensional structure with protrusion and recessed portions. By adding vertical dimensionality to the electrode surfaces, the effective overlapping area between electrodes increases without increasing the planar footprint, thereby maintaining electrostatic capacitance while reducing device area.
Solution Approach 2:
The electrode surfaces are given non-uniform local characteristics through protrusion and recessed portions. This local quality enhancement concentrates the electric field in specific regions, increasing the effective capacitance-generating area within the same overall device dimensions, thus resolving the contradiction between size reduction and capacitance maintenance.
2Area of moving object
If the electrode finger width is reduced to decrease device area, then the device size is reduced, but the electrostatic capacitance decreases
Solution Approach 1:
By introducing protrusion and recessed portions on the side surfaces of electrode fingers, the invention adds a third dimension to the electrode structure. This allows the electrode area to be effectively increased through vertical surface area rather than horizontal expansion, maintaining capacitance while reducing planar device area.
3Quantity of substance
If the number of electrode fingers is increased to increase electrostatic capacitance, then the electrostatic capacitance is improved, but the device area increases
Solution Approach 1:
The invention achieves increased capacitance not by adding more electrode fingers horizontally (which would increase device area) but by enhancing the surface area of existing fingers through protrusion and recessed portions in the vertical dimension. This allows capacitance improvement without proportional increase in device area.
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 results in a smaller acoustic wave device with enhanced electrostatic capacitance, enabling improved performance and efficiency by maintaining the same impedance characteristics, thus addressing the size reduction challenge.
Implementation Method 1
a piezoelectric substrate; and a pair of comb-shaped electrodes located on the piezoelectric substrate
Implementation Method 2
surface acoustic wave (SAW) elements are used in the high-frequency filters. The SAW element is an element in which an interdigital transducer (IDT) including a pair of comb-shaped electrodes is formed on a piezoelectric substrate
Data Source
AI summary
An acoustic wave device includes: a piezoelectric substrate; and a pair of comb-shaped electrodes located on the piezoelectric substrate, each of the comb-shaped electrodes including a plurality of electrode fingers, side surfaces facing each other of the electrode fingers having a plurality of protrusion portions and a plurality of recessed portions arranged in an extension direction of the electrode fingers, ends of the protrusion portions and the recessed portions narrowing.