Switchable RF Front-End Filter for Compact Multi-Band Selectivity
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Solution Overview
Problem
Existing radio-frequency front-end circuits face challenges in supporting multiple bands due to the increase in the number of filters required, leading to size limitations and inefficiencies in filter design.
Innovation Solution
A compact filter device is developed, utilizing a switch to interchange the positions of series-arm and parallel-arm resonant circuits, allowing for two filter characteristics with interchanged pass bands and attenuation bands, reducing the number of elements needed and minimizing size while maintaining high selectivity and attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple filters are used to support multiple bands, then multi-band capability is achieved, but the number of elements increases and size reduction is hindered
Solution Approach 1:
The patent applies multi-functionality by enabling a single filter device to support multiple frequency bands through switchable resonant circuits. The filter can be configured to pass different bands (e.g., first band via first resonant circuit, second band via second resonant circuit) using a small number of switches, allowing one device to perform multiple band-filtering functions that would traditionally require separate filters for each band
Solution Approach 2:
The patent implements dynamics by making the filter characteristics switchable between different states. The use of switches connected to parallel resonant circuits allows the filter to dynamically change its pass band and attenuation band characteristics based on the switching state, enabling adaptation to different frequency bands without requiring multiple fixed filters
2Adaptability or versatility
If multiple filters are used to support multiple bands, then multi-band capability is achieved, but the device size increases
Solution Approach 1:
The patent applies merging by combining multiple resonant circuits (first resonant circuit with first resonant frequency and second resonant circuit with second resonant frequency) into a single filter device structure. These resonant circuits are connected in parallel with switching elements, allowing the device to function as multiple band filters integrated into one compact unit, thereby reducing the overall volume compared to using separate physical filters for each band
3Adaptability or versatility
If traditional multi-band filter configuration is used, then multi-band support is achieved, but attenuation performance deteriorates
Solution Approach 1:
The patent applies local quality by providing different resonant circuits optimized for specific frequency bands within the same filter device. The first resonant circuit is tuned for the first band with appropriate attenuation characteristics, while the second resonant circuit is tuned for the second band, allowing each resonant circuit to have specialized local characteristics that ensure high attenuation performance for its designated band while maintaining multi-band 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 solution enables a compact, multi-band capable filter device that supports multiple frequency bands with improved attenuation and reduced loss, achieving high-selectivity filter characteristics and efficient size reduction.
Implementation Method 1
a first resonant circuit disposed in a first path that connects an input terminal and an output terminal and having at least one first resonant frequency, a second resonant circuit disposed in a second path that connects the input terminal and the output terminal and having at least one second resonant frequency different from the at least one first resonant frequency
Data Source
AI summary
A filter includes a first resonant circuit having one or more first resonant frequencies, a second resonant circuit having one or more second resonant frequencies different from the first resonant frequency, and a switch connected to the first resonant circuit and the second resonant circuit. The switch switches between a first state in which a radio-frequency signal of the first resonant frequency flows from an IN terminal to an OUT terminal via the first resonant circuit and a radio-frequency signal of the second resonant frequency flows from the IN terminal to ground via the second resonant circuit and a second state in which a radio-frequency signal of the first resonant frequency flows from the IN terminal to ground via the first resonant circuit and a radio-frequency signal of the second resonant frequency flows from the IN terminal to the OUT terminal via the second resonant circuit.