Acoustic Wave Filter Pitch Layout for Higher Power Handling
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Solution Overview
Problem
Existing acoustic wave filters face challenges in enhancing electric power handling capability due to local heat generation and electrochemical migration at anti-resonant frequencies, particularly with increased demand for higher frequencies and reduced electrode finger distances.
Innovation Solution
The acoustic wave filter design includes series and parallel arms with specific configurations of acoustic wave resonators, where electrode finger pitches are varied to minimize heat generation and improve power handling. Specifically, the mth resonator in the series arm has the smallest pitch, and the mth resonator in the parallel arm has the largest pitch, with resonant frequencies positioned outside the pass band to reduce heat density and enhance power handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple resonators with the same electrode finger pitch are connected in series to improve electric power handling capability, then the series arm resonator can be split into multiple resonators, but the electric power handling capability is still insufficient due to local heat generation at anti-resonant frequencies
Solution Approach 1:
The patent applies local quality by varying the electrode finger pitch in different resonators within the series arm. Specifically, resonators are designed with different pitch values (e.g., first pitch for first resonator, second pitch for second resonator) so that each resonator has distinct electrical characteristics. This local differentiation ensures that anti-resonant frequencies of individual resonators are distributed across different frequency ranges, preventing simultaneous high voltage buildup at the same location and thereby reducing local heat generation while maintaining overall power handling capability.
2Speed
If the distance between electrode fingers is shortened to meet higher frequency demands, then the operating frequency can be increased, but the electric power handling capability requires further improvement due to increased heat generation
Solution Approach 1:
The patent applies segmentation by dividing the series arm into multiple resonators with different electrode finger pitches. This segmentation allows the filter to operate at higher frequencies (shorter wavelengths) while distributing the power handling burden across multiple resonators. Each resonator can be optimized for specific frequency ranges, and the varied pitches ensure that high voltage stress is distributed spatially and spectrally, preventing localized thermal runaway even at higher operating frequencies.
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 effectively reduces power consumption and heat generation, enhancing the electric power handling capability of the acoustic wave filters, especially at high frequencies and anti-resonant frequencies.
Implementation Method 1
Each of the n acoustic wave resonators includes multiple electrode fingers
Implementation Method 2
local heat generation due to high voltage at the anti-resonant frequency causes electrochemical migration
Data Source
AI summary
An acoustic wave filter includes an input end, an output end, and a series arm connecting the input end and the output end. The series arm includes n (n=3) acoustic wave resonators connected in series in an order of first, second, and third acoustic wave resonators. The first, second, and third acoustic wave resonators include multiple electrode fingers. The first, second, and third acoustic wave resonators include an mth acoustic wave resonator (m is a natural number of 1<m<n, where m=2). An electrode finger pitch of the second acoustic wave resonator is smallest among electrode finger pitches of the first, second, and third acoustic wave resonators.