Split Shunt Resonator Layout for Acoustic Filter Isolation
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Solution Overview
Problem
Acoustic wave filters face performance degradation due to electromagnetic coupling effects from magnetic fields generated by current flowing through shunt resonators, leading to reduced isolation and rejection specifications.
Innovation Solution
Splitting shunt resonators into pairs positioned symmetrically or anti-parallel to each other to cancel magnetic fields, resulting in improved isolation and rejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shunt resonators are used in acoustic wave filters, then the filter can be implemented with standard topology, but magnetic fields generated by current flowing through shunt resonators cause electromagnetic coupling effects that degrade isolation and rejection specifications
Solution Approach 1:
The patent applies magnetic field cancellation by positioning shunt resonators to generate opposing magnetic fields that neutralize each other. Current flowing through strategically placed shunt resonators creates magnetic fields in opposite directions, converting the harmful magnetic field interference into a beneficial cancellation effect that improves isolation and rejection specifications
Solution Approach 2:
The patent introduces asymmetric positioning of shunt resonators relative to series resonators. By placing shunt resonators at different locations (e.g., one closer to the input, another closer to the output) rather than symmetric positions, the magnetic fields generated create a cancellation pattern that reduces electromagnetic coupling effects while maintaining filter functionality
2Reliability
If shunt resonators are positioned to cancel magnetic fields, then isolation and rejection improve to -75 dB to -85 dB, but the device complexity increases due to additional positioning constraints
Solution Approach 1:
The patent segments the filter design by dividing the shunt resonator placement into distinct strategic positions along the signal path. Instead of treating all shunt resonators uniformly, the invention specifies particular locations for each shunt resonator relative to series resonators, allowing magnetic field cancellation to be achieved through systematic segmentation of the filter topology
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
Enhances isolation and rejection performance by achieving -75 dB to -85 dB rejection levels in deep rejection regions, optimizing die area usage without increasing costs.
Implementation Method 1
current flowing through the second shunt acoustic wave resonator generates a magnetic field that at least partly cancels a magnetic field generated by current flowing through the first shunt acoustic wave resonator
Data Source
AI summary
Aspects of this disclosure relate to an acoustic wave filter that includes a first shunt acoustic wave resonator and a second shunt acoustic wave resonator configured such that current flowing through the second shunt acoustic wave resonator generates a magnetic field that at least partly cancels a magnetic field generated by current flowing through the first shunt acoustic wave resonator. For example, current flowing through the second shunt acoustic wave resonator can generate a magnetic field in an opposite direction than a magnetic field generated by current flowing through the first shunt acoustic wave resonator. In embodiments, the first shunt acoustic wave resonator can be on an opposite side of a series acoustic wave resonator than the second shunt acoustic wave resonator in physical layout. Related acoustic wave filter dies, multiplexers, radio frequency modules, radio frequency systems, wireless communication devices, and methods are disclosed.