Switched Acoustic Resonator Filters for Wide Frequency Tuning
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Solution Overview
Problem
Current miniature tunable filters have limited frequency tuning ranges due to the electromechanical coupling coefficient of commercially available acoustic resonators, making them unsuitable for the wide band operating frequency bands of current and future wireless communication systems.
Innovation Solution
A tunable filter design utilizing multiple acoustic wave resonators within tunable resonator units, with switches to select different resonators, allowing for a broad frequency tuning range by overlapping the band reject or band pass regions of individual resonators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional microwave tunable filters are used, then frequency tuning capability is provided, but the filter size becomes too large and expensive for commercial wireless applications
Solution Approach 1:
The patent replaces traditional microwave mechanical/electrical tunable filter structures with acoustic wave resonators (SAW, BAW, or FBAR). These acoustic resonators provide frequency tuning capability through acoustic wave phenomena rather than microwave electrical circuits, enabling compact filter designs that maintain tunability while dramatically reducing size and cost for commercial wireless applications
Solution Approach 2:
The patent changes the fundamental operating parameter from microwave frequency electrical signals to acoustic wave frequencies. By using acoustic resonators that operate at different resonant frequencies, the system achieves frequency tuning through acoustic resonance characteristics rather than traditional microwave circuit tuning, enabling smaller filter designs with adequate tuning range
2Volume of moving object
If acoustic wave resonators are used to reduce filter size, then compact design is achieved, but the frequency tuning range is limited by the electromechanical coupling coefficient
Solution Approach 1:
The patent divides the filter into multiple separate acoustic resonator units, each with its own switch. Instead of relying on a single resonator with limited tuning capability, the system segments the frequency tuning function across multiple resonators operating at different frequencies. This allows the filter to achieve a broader overall tuning range by switching between or combining multiple resonator responses, overcoming the limitation of individual resonator coupling coefficients
Solution Approach 2:
The patent makes each acoustic resonator unit universally applicable to different frequency bands through the switching mechanism. Each resonator can be selectively activated to provide different frequency responses, and the combination of multiple resonators creates a multi-functional system that can cover wide frequency ranges. The switches enable each resonator to serve multiple frequency tuning purposes, achieving both compact size and broad tuning range
3Adaptability or versatility
If multiple acoustic resonators are used to expand tuning range, then frequency coverage increases, but device complexity increases
Solution Approach 1:
The patent introduces dynamic switching control to manage multiple acoustic resonators. Each resonator unit is equipped with a switch that can dynamically connect or disconnect specific resonators based on the desired frequency response. This dynamic configuration allows the system to adapt to different frequency requirements without permanently fixing the complex multi-resonator structure, reducing the practical complexity while maintaining broad tuning capability
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 design achieves a significantly broader frequency tuning range compared to traditional filters, making it suitable for modern wireless communication systems while maintaining a compact, lightweight, and cost-effective solution.
Implementation Method 1
acoustic wave resonators, such as surface acoustic wave (SAW) resonators, bulk acoustic wave (BAW) resonators and film bulk acoustic resonators (FBAR)
Implementation Method 2
surface acoustic wave (SAW) resonators
Implementation Method 3
bulk acoustic wave (BAW) resonators
Implementation Method 4
Each tunable resonator unit also has a first switch configured to select one of the plurality of acoustic wave resonators of the tunable resonator unit at a time
Data Source
AI summary
A tunable filter using acoustic resonators is disclosed. A tunable filter includes a plurality of tunable resonator units (20). Each tunable resonator unit (20) has acoustic wave resonators (12). Each acoustic wave resonator is associated with a different tunable frequency. Each tunable resonator unit also has a first switch (22) configured to select one of the plurality of acoustic wave resonators of the tunable resonator unit at a time. The first switches of the plurality of tunable resonator units are coupled to cooperatively select one acoustic wave resonator in each one of the plurality of tunable resonator units, where a selected acoustic wave resonator in a tunable resonator unit of the plurality of tunable acoustic resonator units is associated with a same tunable frequency response as the other selected acoustic resonators of the others of the plurality of tunable acoustic resonator units. The selection results in an overall tunable frequency response.