Variable Filter Circuit With Two-Reactance Bandwidth Tuning
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Solution Overview
Problem
Existing variable filter circuits require a large number of variable reactance elements to adjust center frequency and bandwidth, leading to increased size and complexity in control due to the need for multiple reactance components.
Innovation Solution
A variable filter circuit configuration using only two variable reactance elements, one in a serial arm and one in a parallel arm, with series and parallel reactance elements to achieve frequency adjustment and attenuation pole control, allowing for miniaturization and simplified control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple variable reactance elements are used to adjust center frequency and bandwidth, then frequency adjustment capability is improved, but device size increases
Solution Approach 1:
The patent combines multiple reactance adjustment functions into a single variable reactance element by using a ladder configuration where one variable reactance in the serial arm and one variable reactance in the parallel arm work together to control both center frequency and bandwidth. This merging approach reduces the total number of variable reactance elements from three or more to just two, thereby reducing circuit size while maintaining frequency adjustment capability.
Solution Approach 2:
Each variable reactance element is designed to perform multiple functions simultaneously. The variable reactance in the serial arm and the variable reactance in the parallel arm collectively control both the center frequency and the bandwidth of the pass band, as well as adjust attenuation poles. This multi-functionality allows two elements to achieve what traditionally required three or more elements, reducing overall circuit size.
2Adaptability or versatility
If multiple variable reactance elements are used to adjust center frequency and bandwidth, then frequency adjustment capability is improved, but control complexity increases
Solution Approach 1:
The patent merges the control functions of multiple variable reactance elements into a simplified two-element system. By using one variable reactance in the serial arm and one in the parallel arm within a ladder configuration, the control system only needs to manage two elements instead of three or more, reducing control complexity while maintaining the ability to adjust center frequency and bandwidth.
Solution Approach 2:
The patent employs dynamic control where the two variable reactance elements can be adjusted independently to achieve different filter characteristics. The serial arm variable reactance and parallel arm variable reactance work in conjunction to dynamically control both center frequency and bandwidth, as well as attenuation pole positions, providing flexible control with minimal elements.
3Adaptability or versatility
If multiple variable reactance elements are used to achieve resonant frequencies on lower and higher sides of pass band, then frequency coverage is improved, but the number of components increases
Solution Approach 1:
The patent combines the functions of multiple reactance elements into a streamlined two-element configuration. The variable reactance in the serial arm and the variable reactance in the parallel arm work together to provide resonant frequencies on both lower and higher sides of the pass band, achieving comprehensive frequency coverage with fewer components.
Solution Approach 2:
Each variable reactance element is designed with multi-functionality to control multiple aspects of filter performance. The serial arm variable reactance and parallel arm variable reactance collectively provide frequency coverage across the entire operating range, including lower and higher resonant frequencies, while also controlling center frequency, bandwidth, and attenuation poles, all with just two components.
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
This configuration enables efficient frequency adjustment and steep attenuation characteristics while reducing the overall size and complexity of the circuit, allowing for compact and effective frequency control.
Implementation Method 1
a frequency at which the variable reactance element and the parallel reactance element resonate is lower than a frequency at which the variable reactance element and the series reactance element resonate
Implementation Method 2
a frequency at which the variable reactance element and the parallel reactance element resonate is lower than a frequency at which the variable reactance element and the series reactance element resonate
Data Source
AI summary
The present disclosure provides a variable filter circuit capable of controlling a band width and a center frequency of a pass band, and also capable of suppressing the total number of pieces of variable reactance. That is, a variable filter circuit includes a serial arm in which a plurality of circuit elements are connected in series with respect to a signal path and a parallel arm in which a plurality of circuit elements are connected in parallel with respect to the signal path, wherein the serial arm and the parallel arm each includes a variable reactance element, a series reactance element that is connected in series to the variable reactance element and resonates therewith, and a parallel reactance element that is connected in parallel to the variable reactance element and resonates therewith.