Acoustic Wave Filter Resonator Layout for Broader RF Passbands
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Solution Overview
Problem
Current acoustic wave filters in RF communication systems face challenges in achieving a broader passband while maintaining a high quality factor, as conventional designs often degrade admittance at frequencies below the resonant frequency, limiting their effectiveness in ultrawide bandwidth applications.
Innovation Solution
The acoustic wave filter design incorporates a plurality of series and shunt resonators, where the first group of series resonators has a raised frame region to improve the quality factor above the resonance frequency, and the second group lacks a raised frame region to broaden the bandwidth, with shunt resonators strategically placed to enhance rejection band characteristics, thereby optimizing the filter's performance across the target passband.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a raised frame region is added to resonators to improve quality factor above resonance frequency, then the quality factor is improved, but the bandwidth is reduced
Solution Approach 1:
The patent applies local quality by differentiating the resonator structure into two groups: resonators with raised frame regions (to improve Q-factor above resonance) and resonators without raised frame regions (to broaden bandwidth). This localized structural differentiation allows each group to optimize for its specific function while working together in the filter assembly.
Solution Approach 2:
The filter's series resonators are segmented into two distinct groups based on their frame structure. The first group has raised frame regions for high Q-factor performance, while the second group lacks raised frames for bandwidth extension. This segmentation resolves the contradiction by distributing different functional characteristics across subgroups.
2Reliability
If conventional acoustic wave filter design is used to maintain high quality factor, then quality factor is maintained, but passband bandwidth is limited
Solution Approach 1:
The patent changes the structural parameter of the resonators by introducing a raised frame region configuration. This parameter change affects the resonator's electrical characteristics, enabling improved Q-factor above resonance frequency while the selective application across different resonators maintains overall bandwidth.
Solution Approach 2:
By applying the raised frame structure only to specific resonators (first group) rather than all resonators, the patent achieves local optimization of quality factor without globally constraining the passband bandwidth, as the second group of resonators provides bandwidth extension.
3Reliability
If resonators are configured to improve quality factor above resonance frequency, then quality factor is improved, but admittance degradation occurs below resonance frequency
Solution Approach 1:
The patent converts the potential harm of admittance degradation below resonance frequency into a benefit by strategically placing resonators without raised frame regions in the second group. These resonators compensate for the admittance degradation, transforming the harmful effect into an opportunity for bandwidth extension while maintaining overall filter performance.
Solution Approach 2:
The asymmetric configuration of raised frame regions in only the first group of resonators creates complementary frequency responses. The raised frames improve Q-factor above resonance, while the absence of raised frames in the second group maintains better admittance characteristics below resonance, creating an asymmetric but balanced overall response.
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 enhances the filter's quality factor above the resonance frequency while maintaining it below, thereby broadening the passband and reducing insertion loss, making it suitable for ultrawide bandwidth applications.
Implementation Method 1
An acoustic wave filter, which is used widely in the wireless communication field, can include a plurality of resonators arranged to filter a radio frequency signal
Implementation Method 2
Example acoustic wave filters include surface acoustic wave (SAW) filters and/or bulk acoustic wave (BAW) filters
Implementation Method 3
Example acoustic wave filters include surface acoustic wave (SAW) filters and/or bulk acoustic wave (BAW) filters
Data Source
AI summary
Acoustic wave filters operating at wider passband with enhanced frequency response are provided herein. In certain embodiments, an acoustic wave filter comprises an input port and an output port, a plurality of series resonators electrically connected in series between the input port and the output port, the plurality of series resonators including a first group of resonators and a second group of resonators, each resonator of the first group of resonators having a raised frame region, the second group of resonators including at least one resonator having its resonance frequency closest to one edge of a target passband that is closer to its anti-resonance frequency lacking any raised frame region such as to broaden a bandwidth of the target passband, and a plurality of shunt resonators each being electrically connected between respective series resonators and a ground.