Switchable Micro-Acoustic RF Filter for Attenuation-Loss Tradeoff
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Solution Overview
Problem
Conventional micro-acoustic RF filters face challenges in achieving low insertion loss and high out-of-band attenuation simultaneously, leading to space and cost inefficiencies due to the need for multiple filters and increased power consumption when interference is detected.
Innovation Solution
A configurable micro-acoustic RF filter with switchable filter subsections, allowing selection between individual and concatenated sections to adjust attenuation based on interference detection, utilizing symmetrical TEE or PI configurations and shunt-connected inductances for parasitic capacitance compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a filter with high out-of-band attenuation is used, then crosstalk and interference are reduced, but insertion loss in the passband increases
Solution Approach 1:
The filter is divided into multiple filter subsections (first, second, third) that can be independently connected or disconnected. Each subsection contains resonators that can be selectively activated. This segmentation allows the filter to dynamically adjust its attenuation characteristics by connecting only the necessary subsections, thereby achieving high out-of-band attenuation when needed while minimizing insertion loss during normal operation.
Solution Approach 2:
The filter employs switches (first, second, third switches) that dynamically reconfigure the filter subsections based on detected interference levels. When interference is detected in the stopband, the switches connect additional subsections to increase out-of-band attenuation. When no interference is present, the switches disconnect subsections to minimize insertion loss. This dynamic adaptation resolves the contradiction between attenuation and insertion loss.
2Adaptability or versatility
If two parallel filters are used to provide both low insertion loss and high out-of-band attenuation, then both requirements are met, but device space and cost increase
Solution Approach 1:
Multiple filter subsections are merged into a single filter structure with shared components. The first, second, and third filter subsections are connected in a configuration where they can be selectively activated, combining the functionality of what would traditionally require separate filters. This merging reduces device space while maintaining the ability to provide both low insertion loss and high out-of-band attenuation as needed.
Solution Approach 2:
Each filter subsection is designed to serve multiple functions: they provide both passband transmission and stopband attenuation capabilities. The same subsections that provide low insertion loss when activated individually also contribute to out-of-band attenuation when combined with other subsections. This multi-functionality eliminates the need for separate specialized filters, reducing overall device space and component count.
3Object-affected harmful factors
If filter subsections are concatenated to increase out-of-band attenuation, then interference suppression is improved, but filter complexity and component count increase
Solution Approach 1:
The filter is segmented into modular subsections that can be independently controlled. Each subsection contains resonators and can be connected or disconnected via switches. This segmentation allows interference suppression to be achieved by activating only the necessary subsections, rather than permanently incorporating all possible attenuation-providing components, thereby reducing overall filter complexity while maintaining interference suppression capability.
Solution Approach 2:
The filter subsystem includes interference detection capability that automatically controls the switching of filter subsections. When interference is detected, the system self-adjusts by connecting additional subsections to increase attenuation. This self-service mechanism eliminates the need for complex external control circuitry, reducing overall device complexity while achieving effective interference suppression through adaptive subsection concatenation.
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 filter achieves adaptive reception by minimizing crosstalk and interference while reducing component count and space requirements, allowing for efficient signal processing with controlled power consumption.
Implementation Method 1
a shunt connected inductance may be coupled to the third terminal of the switch to compensate the parasitic capacitance of the switch relative to ground potential
Implementation Method 2
The first and second filter subsections each include at least one serially connected and at least one shunt connected micro-acoustic resonator
Data Source
AI summary
A configurable micro-acoustic RF filter comprises first and second filter subsections (140, 150) and at least one switch (160) to selectively bypass or activate the second filter subsection (150). The filter sections include at least one serially connected and at least one shunt connected micro-acoustic resonator.