Reconfigurable RF Filter Circuit for Multi-Band Size Reduction
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Solution Overview
Problem
Increasing number of frequency bands supported by wireless communication devices leads to larger device sizes and increased costs due to the need for multiple RF filters and support circuitry.
Innovation Solution
Implementation of reconfigurable RF filters using series and shunt resonators with switchable impedance circuits, allowing flexible frequency band selection and reduction in the number of physical filters required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple RF filters are added to support more frequency bands, then the number of supported frequency bands increases, but the device size increases
Solution Approach 1:
A single filter structure is designed to perform multiple functions by supporting multiple frequency bands through reconfigurable elements. The filter can be dynamically adjusted to pass different frequency bands (e.g., LTE bands 3, 7, 13, 17) using switchable resonators and impedance transformation circuits, eliminating the need for separate dedicated filters for each band.
Solution Approach 2:
The filter incorporates dynamic reconfiguration capabilities through electronically controllable switches (e.g., SPDT switches) that can change the filter's frequency response in real-time. By switching between different resonator configurations and impedance values, the filter adapts its passband to match the currently required frequency band without physical replacement or addition of components.
2Adaptability or versatility
If multiple RF filters are added to support more frequency bands, then the number of supported frequency bands increases, but the device cost increases
Solution Approach 1:
The filter design uses a universal structure with reconfigurable elements that can serve multiple frequency bands. This includes shared resonators, common impedance transformation circuits, and reusable switch matrices, allowing a single filter module to replace what would traditionally require multiple separate filter modules, thereby reducing overall component count and manufacturing cost.
Solution Approach 2:
Multiple filter functions are merged into a single integrated filter structure. The design combines multiple resonators, switch networks, and impedance transformation circuits into one unified filter module that can be controlled to provide different frequency responses, consolidating what would traditionally be separate discrete filter components into a single cost-effective unit.
3Adaptability or versatility
If filter complexity is increased to support more frequency bands, then the number of supported frequency bands increases, but the device complexity increases
Solution Approach 1:
The filter employs dynamic reconfiguration through electronically controlled switches that can change the circuit topology on-demand. Instead of having fixed complex structures for each frequency band, the filter uses a base structure with switchable elements (e.g., SPDT switches connecting different resonators and impedance circuits) that dynamically reconfigure the filter response to match the required band, simplifying the overall design while maintaining multi-band capability.
Solution Approach 2:
The filter achieves multi-band support by changing key circuit parameters such as resonator connections, impedance values, and circuit topologies through electronic control. By varying these parameters dynamically via switch control, the filter can adapt its frequency response without requiring fundamentally different structures for each band, thereby managing complexity through parameter variation rather than structural proliferation.
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
Reduces the number of filters needed, minimizing device size and cost while maintaining effective signal processing capabilities.
Implementation Method 1
The filter includes first resonators coupled in series between an input and an output, a second resonator coupled as a shunt between a node in the series and a reference voltage
Data Source
AI summary
An example filter for radio frequency (RF) signals in a radio includes first resonators coupled in series between an input and an output; a second resonator coupled as a shunt between a node in the series and a reference voltage; and a first circuit coupled in parallel with one of the first resonators, the first circuit including a switch coupled in series with an impedance.