Acoustic Microwave Filter Synthesis With Resonator Parasitic Modeling
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Solution Overview
Problem
There is a need for improved microwave acoustic wave filters that provide enhanced performance, smaller size, lower cost, and tunability, while incorporating the compound nature of acoustic wave resonators directly into the network synthesis process.
Innovation Solution
The method involves designing an acoustic microwave filter by selecting an initial filter circuit structure with resonant and reactive elements, transforming these elements into acoustic resonator models, and optimizing the circuit design to achieve specific frequency response requirements, including the incorporation of parasitic effects and element removal optimization to create a final filter circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional image filter design methods are used with acoustic wave resonators, then the filter can be constructed with established circuit elements, but the filter size and performance are limited by conventional approaches
Solution Approach 1:
The patent replaces traditional mechanical circuit elements (inductors, capacitors, transformers) with acoustic wave resonators that operate on acoustic principles. This substitution enables more compact filter designs while maintaining or improving performance characteristics, as acoustic resonators can achieve higher Q-factors and smaller physical dimensions compared to their electromagnetic counterparts.
Solution Approach 2:
The patent transforms the filter design by changing the fundamental operating parameters from electromagnetic resonance to acoustic resonance. By using acoustic wave resonators with specific resonant frequencies and Q-factors, the filter achieves improved size-performance trade-offs. The network synthesis method allows optimization of acoustic resonator parameters (mass, stiffness, damping) to meet specific filter requirements while minimizing physical footprint.
2Reliability
If network synthesis is applied to acoustic wave filters, then the filter performance can be optimized according to frequency response requirements, but the design complexity increases
Solution Approach 1:
The patent applies network synthesis methods in advance to determine the optimal configuration and parameters of acoustic resonators before physical construction. By pre-calculating the required resonant frequencies, Q-factors, and coupling coefficients based on desired frequency response characteristics, the design process becomes more systematic and less trial-and-error oriented, reducing overall complexity despite the advanced mathematics involved.
Solution Approach 2:
The patent develops a universal network synthesis framework that can be applied to various acoustic wave filter configurations (series, parallel, bridged-T, lattice) using the same fundamental mathematical approach. This universal methodology reduces design complexity by providing a consistent set of procedures and equations that work across different filter topologies, rather than requiring separate design methods for each configuration.
3Area of stationary object
If acoustic wave resonators are used to reduce filter size, then compactness is achieved, but the compound nature of resonators (resonance and anti-resonance frequencies) must be carefully managed
Solution Approach 1:
The patent converts the potentially harmful effect of anti-resonance frequencies into a beneficial feature by deliberately positioning anti-resonances to provide automatic stopband rejection. Instead of treating anti-resonances as parasitic effects to be eliminated, the design methodology uses them to enhance filter performance, creating sharp rejection bands without requiring additional circuit elements, thus maintaining compactness while managing the compound nature of resonators.
Solution Approach 2:
The patent segments the filter design into independent acoustic resonator units, each with its own resonance and anti-resonance characteristics. By carefully selecting and positioning these segmented resonators with specific frequency characteristics, the compound nature of each resonator is managed individually, and their combined effect achieves the desired overall frequency response while maintaining compact dimensions.
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 results in better-performing, lower-cost microwave filters with improved frequency response characteristics, suitable for demanding applications in mobile communications and other RF frontend systems, offering tunability and reduced size.
Implementation Method 1
Acoustic Wave (AW) resonators, specifically quartz bulk acoustic wave (BAW) resonators
Implementation Method 2
The equivalent circuit of an AW resonator has two resonances closely spaced in frequency called the 'resonance' frequency and the 'anti-resonance' frequency
Data Source
AI summary
A method of designing an acoustic microwave filter in accordance with frequency response requirements. The method comprises selecting an initial filter circuit structure including a plurality of circuit elements comprising at least one resonant element and at least one other reactive circuit element, selecting circuit response variables based on the frequency response requirements, selecting a value for each of the circuit elements based on the selected circuit response variables to create an initial filter circuit design, transforming the resonant element(s) and the other reactive circuit element(s) of the initial filter circuit design into at least one acoustic resonator model to create an acoustic filter circuit design, adding parasitic effects to the acoustic filter circuit design to create a pre-optimized filter circuit design, optimizing the pre-optimized filter circuit design to create a final filter circuit design, and constructing the acoustic microwave filter based on the final filter circuit design.