Multi-Resonant Shunt Acoustic Wave Filter for Wideband Rejection
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Solution Overview
Problem
Designing acoustic wave filters with rejection over a relatively wide frequency range is challenging, as existing filters struggle to achieve stringent rejection specifications without significantly degrading the pass band, especially in radio frequency electronic systems.
Innovation Solution
The implementation of shunt acoustic wave resonators with multiple resonant frequencies, which include interdigital transducer electrodes with different pitches, allows for improved out-of-band rejection by creating multiple notches in the frequency response, thereby enhancing the filter's rejection capabilities without adding additional components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional resonators are added to increase rejection frequency range, then rejection capability is improved, but device complexity increases
Solution Approach 1:
The patent applies multi-functionality by designing a single resonator that performs multiple rejection functions across different frequency ranges. The resonator incorporates multiple IDT electrodes with different pitches (e.g., first pitch for 2.4 GHz band rejection, second pitch for 5 GHz band rejection), allowing one resonator to provide rejection capabilities that would traditionally require multiple separate resonators. This resolves the contradiction by making one component serve multiple purposes.
Solution Approach 2:
The patent merges multiple rejection functions into a single resonator structure. By combining IDT electrodes with different pitches within one resonator, the design consolidates what would traditionally be separate components into one unified structure. This merging reduces the total number of resonators needed while maintaining comprehensive rejection capability across multiple frequency bands.
2Reliability
If more resonators are used to achieve stringent rejection specifications, then rejection performance is improved, but pass band degradation increases
Solution Approach 1:
The patent applies local quality by designing resonators with specific IDT electrode configurations tailored for particular rejection needs. Each IDT electrode group with a specific pitch is optimized for rejecting particular frequency bands while being positioned and configured to minimize impact on the pass band. This localized optimization allows stringent rejection specifications to be met without degrading pass band performance, as each part of the resonator is specifically designed for its local function.
3Adaptability or versatility
If additional resonators are added to expand rejection frequency range, then frequency range for rejection is improved, but device area increases
Solution Approach 1:
The resonator achieves multi-functionality by incorporating IDT electrodes with multiple different pitches within a single device footprint. The first IDT electrodes with a first pitch provide rejection for one frequency band, while second IDT electrodes with a second pitch provide rejection for another frequency band. This allows the device to cover a wide rejection frequency range without requiring proportionally more device area, as multiple functions are integrated into one compact structure.
Solution Approach 2:
The patent employs a nesting principle by placing multiple IDT electrode structures with different pitches within the same resonator body. The different pitch IDT electrodes are nested within the overall resonator structure, allowing multiple rejection functions to coexist in a compact arrangement. This nesting enables expanded frequency range coverage without linearly increasing the 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 approach enables acoustic wave filters to meet stringent rejection specifications with fewer resonators, increasing the frequency range for rejection while maintaining the pass band integrity, thus improving the overall performance of radio frequency filters.
Implementation Method 1
A surface acoustic wave resonator can include an interdigital transductor electrode on a piezoelectric substrate. The surface acoustic wave resonator can generate a surface acoustic wave on a surface of the piezoelectric layer on which the interdigital transductor electrode is disposed.
Implementation Method 2
The first shunt acoustic wave resonator has at least a first resonant frequency and a second resonant frequency. The series acoustic wave resonators and the shunt acoustic wave resonators are together arranged to filter a radio frequency signal.
Data Source
AI summary
Aspects of this disclosure relate to an acoustic wave resonator having at least two resonant frequencies. An acoustic wave filter can include series acoustic wave resonators and shunt acoustic wave resonators together arranged to filter a radio frequency signal. A first shunt resonator of the shunt acoustic wave resonators can include an interdigital transducer electrode and have at least a first resonant frequency and a second resonant frequency. Related acoustic wave resonators, multiplexers, wireless devices, and methods are disclosed.