Microwave Acoustic Filter Design Using Parasitic-Aware Network Synthesis
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Solution Overview
Problem
Current microwave acoustic wave filters face challenges in achieving improved performance, smaller size, and lower cost while incorporating tunability, particularly in the frequency range of 500-3500 MHz, where existing designs struggle to meet demanding electrical and environmental requirements effectively.
Innovation Solution
A network synthesis technique is employed to design acoustic microwave filters by selecting an initial filter circuit structure with resonant and reactive elements, transforming them into acoustic resonator models, and optimizing the circuit design to incorporate parasitic effects, allowing for the creation of pre-optimized and final filter designs that meet specific frequency response requirements.
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 designed with established circuit structures, but the filter size, cost, and performance are limited and cannot meet demanding requirements
Solution Approach 1:
The patent applies network synthesis methodology which fundamentally changes the design parameters and mathematical approach from traditional image methods. This involves using complex polynomial ratios to represent filter responses and synthesizing circuit element values through systematic mathematical procedures, enabling optimized performance while managing design complexity through structured methods
Solution Approach 2:
The patent replaces traditional mechanical/circuit-based design intuition with a systematic mathematical synthesis approach. By using network synthesis theory, the design process transitions from empirical circuit tuning to calculated element values derived from desired frequency response specifications, improving reliability while providing a clear design framework
2Reliability
If filter design optimizes for performance, then frequency response characteristics improve, but filter size and cost increase
Solution Approach 1:
The patent uses network synthesis to systematically determine optimal circuit element values that achieve desired frequency response characteristics. By calculating precise L and C values from polynomial ratios, the method optimizes performance while avoiding unnecessary component proliferation, thereby controlling size and cost
3Adaptability or versatility
If existing acoustic wave filter designs are used, then the filters can operate in microwave frequency ranges, but they cannot achieve tunability or meet demanding environmental requirements
Solution Approach 1:
The patent enables tunability by incorporating variable circuit elements into the network synthesis framework. The synthesized filter design allows dynamic adjustment of L and C values to change operating frequency and response characteristics, providing adaptability while maintaining performance through the systematic design approach
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
The approach results in better-performing, lower-cost microwave filters with improved frequency response characteristics, enabling smaller size and tunability, suitable for demanding applications such as RF frontends in mobile communications devices.
Implementation Method 1
The equivalent circuit of an AW resonator has two resonances closely spaced in frequency called the 'resonance' frequency and the 'anti-resonance' frequency
Implementation Method 2
Acoustic Wave (AW) resonators, specifically quartz bulk acoustic wave (BAW) resonators
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 lossless 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.