Shared-Reflector SAW Resonators for High Q in Less Area
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Solution Overview
Problem
Existing acoustic wave filters require a large area for reflectors, which increases the size and complexity of RF communication systems, and there is a need for improved designs that reduce the number of reflectors while maintaining high quality factor (Q) performance.
Innovation Solution
The implementation of a dual resonator structure with a shared common reflector between two pairs of IDT electrodes, where the common reflector has a larger pitch distance than the individual electrode pairs, reducing the total reflector area and allowing each resonator to act as a reflector for the other, thereby optimizing space and enhancing Q factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional acoustic wave filters use separate reflectors for each resonator, then each resonator can maintain its quality factor, but the overall device area and complexity increase significantly
Solution Approach 1:
The patent merges the reflector functions by implementing a shared common reflector structure that serves multiple resonators simultaneously. The common reflector is positioned between the first and second IDT pairs and reflects acoustic waves for both resonators, eliminating the need for separate reflectors and reducing overall device area.
Solution Approach 2:
The common reflector performs multiple functions: it serves as the reflector for both the first and second resonators, and additionally functions as a ground electrode providing electrical grounding. This multi-functionality reduces the number of components needed while maintaining resonator performance.
2Reliability
If traditional acoustic wave filters use separate reflectors for each resonator, then each resonator can maintain its quality factor, but the device complexity increases
Solution Approach 1:
The patent combines multiple reflector functions into a single common reflector structure, reducing the number of discrete components from four separate reflectors to one shared reflector plus two side reflectors. This merging simplifies the overall device architecture and reduces manufacturing complexity.
Solution Approach 2:
The common reflector serves dual purposes as both an acoustic wave reflector and a ground electrode, eliminating the need for separate grounding structures and reducing device complexity.
3Area of stationary object
If the common reflector uses a larger pitch distance, then the reflector area is reduced, but the pitch distance must remain equal to or smaller than individual electrode pitches to maintain functionality
Solution Approach 1:
The patent optimizes the pitch distance parameter of the common reflector to balance area reduction with functional requirements. The third pitch distance is set larger than the first pitch distance but equal to or smaller than the second pitch distance, achieving area efficiency while maintaining proper acoustic wave reflection characteristics.
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 design reduces the overall size and complexity of the acoustic wave filter while maintaining or improving the quality factor (Q) performance by sharing reflectors, leading to more efficient use of space and improved signal processing capabilities.
Implementation Method 1
a first pair of IDT electrodes disposed on the substrate, each of the first pair of IDT electrodes including a bus bar and a plurality of fingers extending along a surface of the substrate from the bus bar
Implementation Method 2
a common reflector disposed between the first pair of IDT electrodes and the second pair of IDT electrodes
Implementation Method 3
a respective finger of one IDT electrode arranged interleaved with respective fingers of the other IDT electrode of the first pair of IDT electrodes
Data Source
AI summary
Aspects and embodiments disclosed herein include an acoustic wave device comprising a first pair of IDT electrodes disposed on a substrate, fingers of the first pair of IDT electrodes separated by a first pitch distance from adjacent fingers, a second pair of IDT electrodes disposed on the substrate, fingers of the second pair of IDT electrodes separated by a second pitch distance from adjacent fingers, and a common reflector disposed between the first pair of IDT electrodes and the second pair of IDT electrodes, the common reflector including a plurality of fingers separated from each other by a third pitch distance, which is greater than the first pitch distance and is equal to or smaller than the second pitch distance.