SAW Resonator Floating Metal Blocks for Edge Transverse Modes
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Solution Overview
Problem
Surface acoustic wave (SAW) resonators face issues with transverse mode signals due to high elastic wave velocity in transducer edge gap regions, leading to unwanted ripples in filter characteristics.
Innovation Solution
Incorporating a series of floating metal blocks in the edge regions of the interdigital transducer, which are spaced apart and overlap the edge regions, reducing the elastic wave velocity in these areas and suppressing transverse mode signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If floating metal blocks are added to reduce transverse mode signals, then filter characteristics are improved, but device complexity increases
Solution Approach 1:
The floating metal layer is segmented into multiple discrete floating metal blocks that are spaced apart from each other. This segmentation allows the metal structures to selectively suppress transverse mode signals at edge regions while maintaining simplicity in the center region, thereby improving filter characteristics without excessive complexity
Solution Approach 2:
Floating metal blocks are positioned only in the edge regions of the interdigital transducer where transverse mode signals originate, rather than uniformly across the entire device. This localized approach targets the specific problem area to improve filter characteristics while minimizing the addition of complex structures
2Object-generated harmful factors
If floating metal blocks are used to suppress transverse modes, then manufacturing complexity increases, but transverse mode signals are reduced
Solution Approach 1:
The floating metal blocks are embedded within the temperature compensation layer, nesting the metal structures inside the existing layer structure. This integration allows the floating metal blocks to be incorporated into the device without requiring separate manufacturing steps, thus reducing manufacturing complexity while effectively suppressing transverse mode signals
3Object-generated harmful factors
If a floating metal layer is added to the device, then transverse mode suppression is achieved, but device structure becomes more complex
Solution Approach 1:
Instead of creating a continuous floating metal layer that would add significant structural complexity, the invention extracts only the necessary metal blocks at the edge regions where transverse modes originate. This selective extraction achieves transverse mode suppression while keeping the overall device structure relatively simple
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 implementation of floating metal blocks effectively reduces transverse mode signals, improving the filter characteristics of SAW resonators by matching the elastic wave velocity in edge regions to that of the center region.
Implementation Method 1
reducing the elastic wave velocity in these areas and suppressing transverse mode signals
Implementation Method 2
an interdigital transducer disposed on the piezoelectric substrate
Data Source
AI summary
An acoustic wave device includes a piezoelectric substrate and an interdigital transducer disposed on the piezoelectric substrate, the interdigital transducer including a center region, first and second edge regions, and first and second gap regions, a temperature compensation layer covering the interdigital transducer, and a floating metal layer buried in the temperature compensation layer or disposed on top of the temperature compensation layer. The floating metal layer includes a plurality of floating metal blocks spaced apart from each other and overlapping at least the first and second edge regions of the interdigital transducer.