SAW Electrode End Films for Lower Insertion Loss
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Solution Overview
Problem
Conventional surface acoustic wave (SAW) devices face challenges in reducing insertion loss and energy loss without increasing the size of the device, as existing methods to minimize insertion loss often result in larger module sizes.
Innovation Solution
The SAW device incorporates a substrate with alternately disposed first and second electrodes, a temperature compensation film, and additional films that vertically overlap partial regions of the electrodes and reflectors, made from materials like silicon oxide or aluminum oxide, to suppress energy loss and improve insertion loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the spacing between electrodes is adjusted or multiple SAW devices are used to reduce insertion loss, then insertion loss is reduced, but the overall size of the module increases
Solution Approach 1:
The patent applies local quality by forming additional films only in specific regions where transverse waves are generated (at the ends of interdigitated electrodes), rather than uniformly across the entire device. This localized treatment suppresses transverse wave generation at critical points while maintaining the compact overall structure, thereby reducing insertion loss without increasing module size.
Solution Approach 2:
The additional films act as intermediary elements that mediate between the interdigitated electrodes and the substrate. These films suppress the generation of transverse waves by providing a mechanical impedance mismatch at the electrode ends, thereby reducing energy loss from transverse wave propagation while maintaining the compact electrode configuration.
2Loss of energy
If additional films are formed to suppress transverse wave generation, then energy loss is reduced, but device complexity increases
Solution Approach 1:
The additional films are formed only in localized regions at the ends of the interdigitated electrodes where transverse waves are generated, rather than across the entire device surface. This localized approach suppresses transverse wave generation and reduces energy loss while adding minimal structural complexity to the overall device.
Solution Approach 2:
The patent applies partial action by forming additional films only in the specific regions where transverse wave suppression is needed (at the electrode ends), rather than applying films uniformly across the entire device. This partial treatment is sufficient to reduce energy loss from transverse waves without unnecessarily increasing device complexity.
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 energy loss and insertion loss while maintaining a compact device size by aligning additional films on the temperature compensation film, enhancing the electromechanical coupling factor and reducing transverse wave generation.
Implementation Method 1
A surface acoustic wave (SAW) refers to an acoustic wave propagating along a surface of an elastic substrate
Implementation Method 2
enhancing the electromechanical coupling factor and reducing transverse wave generation
Implementation Method 3
Such an acoustic wave is generated from an electrical signal as a result of piezoelectric effect
Data Source
AI summary
A surface acoustic wave device includes a substrate, a first electrode and a second electrode formed on the substrate to extend along a first direction, wherein the first electrode and the second electrode are alternately disposed along the second direction, one end of the first electrode on one side of the first direction is aligned along the second direction, and one end of the second electrode on the other side of the first direction is aligned along the second direction, a temperature compensation film which covers the first electrode and the second electrode, a first additional film formed on the temperature compensation film to vertically overlap a partial region from the one end of the first electrode on the one side of the first direction, and a second additional film formed on the temperature compensation film to vertically overlap a partial region from the one end of the second electrode.