Elastic Wave Reflector Regions for Dual-Filter Insertion Loss
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Solution Overview
Problem
Existing elastic wave devices with dual filters experience high insertion loss due to energy dissipation when signals from low-frequency and high-frequency filters overlap at common output terminals, leading to undesirable energy loss in both passbands.
Innovation Solution
The elastic wave device is designed with reflectors having specific regions with tailored reflection bands, where the center frequency of the reflection band in one region is lower or higher than in adjacent regions, allowing for balanced reduction of insertion loss by optimizing the placement and pitch of grid electrodes in the reflectors to prevent signal dissipation across frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If common output terminals are used for both low-frequency and high-frequency filters, then device integration is improved, but insertion loss increases due to energy dissipation in the other filter's reflectors
Solution Approach 1:
The reflector is divided into multiple regions (first region, second region, third region, fourth region) with different reflection band characteristics. Each region is responsible for reflecting specific frequency ranges, preventing cross-filter energy dissipation while maintaining common output terminals.
Solution Approach 2:
Different regions of the reflector are designed with locally optimized properties: the first region reflects low-frequency passband signals, the second region reflects high-frequency passband signals, and the third/fourth regions provide additional frequency-specific reflection. This local differentiation allows the single reflector structure to serve multiple frequency bands without causing energy loss in either filter.
2Reliability
If reflectors are designed to cover their respective filter's passband, then passing characteristics are improved, but signals from the other filter are dissipated causing high insertion loss
Solution Approach 1:
The reflector is designed as a multi-functional component that simultaneously serves both the low-frequency filter and the high-frequency filter. By creating multiple regions with different reflection characteristics, a single reflector structure can protect both filters from energy dissipation, eliminating the need for separate reflectors for each filter.
Solution Approach 2:
The reflection band parameters of different reflector regions are specifically adjusted to match the passband characteristics of both filters. The first region's reflection band covers the low-frequency passband, while the second region's reflection band covers the high-frequency passband, allowing the reflector to adapt to multiple frequency requirements.
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 significantly reduces insertion loss in both low- and high-frequency filters by effectively reflecting signals back to their respective filters, maintaining favorable passing characteristics and reducing energy dissipation, thereby enhancing the overall performance of the elastic wave device.
Implementation Method 1
the reflection band in the first region covers the low-frequency passband; and the reflection band in the second region covers the high-frequency passband
Implementation Method 2
Elastic wave resonator 10 includes multiple interdigital transducers (expressed as IDT, hereinafter) 15 between a pair of reflectors 13A and 13B
Data Source
AI summary
A reflector of the elastic wave resonator in an elastic wave device has first and second regions. The second region has third and fourth regions. The first region is located near to the IDTs of the reflector, while the second region is located farther from them. The third region is located nearer to the IDTs in the second region, while the fourth region is located farther from them. As a result that the center frequency of the reflection band in the fourth region is lower than that in the third region, an elastic wave device with low energy loss and insertion loss is provided.