Ladder SAW Filter Dielectric Film Layout for Frequency Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Ladder-type surface acoustic wave filters face frequency fluctuations due to power consumption and heat generation issues, particularly with the first series resonator having the lowest resonance frequency, which degrades the pass characteristics of the filter.
Innovation Solution
The design includes a dielectric film with an inverse temperature coefficient of frequency, where the film thickness is larger over the first series resonator with the lowest resonance frequency, reducing frequency fluctuations and heat generation, while the second series resonator has a thinner film and higher antiresonant frequency to maintain passband integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a uniform dielectric film is formed over all series resonators, then the manufacturing process is simple, but the first series resonator experiences excessive heat generation and frequency fluctuations
Solution Approach 1:
The patent applies local quality by forming a dielectric film selectively only on the first series resonator (having the lowest resonance frequency) while leaving other series resonators without the film. This localized approach addresses the specific heat generation and frequency stability issues of the first resonator without unnecessarily complicating the overall structure or affecting other resonators.
2Reliability
If the dielectric film is formed only on the first series resonator, then frequency stability is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies segmentation by dividing the dielectric film formation process into selective application on specific resonators. The dielectric film is segmented to cover only the first series resonator, allowing independent optimization of each resonator's thermal and frequency characteristics while maintaining manufacturability through targeted processing.
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 reduces frequency fluctuations and heat-related deterioration in the first series resonator, enhancing the power durability and pass characteristics of the ladder-type surface acoustic wave filter.
Implementation Method 1
a dielectric film coupled to at least one of the plurality of series resonators and having an inverse temperature coefficient of frequency to that of the substrate
Implementation Method 2
ladder-type surface acoustic wave filter comprising a substrate, an input terminal, an output terminal
Data Source
AI summary
A ladder-type surface acoustic wave filter assembly includes a plurality of series resonators formed on a substrate and connected between an input terminal and an output terminal. A first series resonator has a lowest resonance frequency among the plurality of series resonator. A parallel resonator formed on the substrate and connected between the plurality of series resonators and the ground terminal. A dielectric film is coupled to at least one of the plurality of series resonators and has an inverse temperature coefficient of frequency to that of the substrate. A film thickness of the dielectric film in a region where the second series resonator is formed is smaller than a film thickness of the dielectric film in a region where the first series resonator is formed.