Resonant Filter Circuit for Narrow RF Transition Bands
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing band-stop filters have wide transition bands, high insertion loss, and poor roll-off coefficients, making them inefficient in separating closely spaced radio frequency signals.
Innovation Solution
A filter circuit design incorporating series and parallel resonance circuits with specific impedance elements, where the resonance frequency of the series resonator is less than that of the parallel resonator, optimizing the passband insertion loss and roll-off coefficient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional band-stop filter designs are used, then the filter can block noise spectrum, but the transition band is wide and insertion loss is high
Solution Approach 1:
The filter is divided into multiple resonant circuits with different functions: series resonant circuits for stopband suppression and parallel resonant circuits for passband transmission. This segmentation allows each circuit to be optimized for its specific function, reducing overall insertion loss while maintaining signal separation performance.
Solution Approach 2:
Different resonant circuits are designed with specific quality factors (Q-values) tailored to their functions. Series resonant circuits have high Q for narrow stopband, while parallel resonant circuits have optimized Q for minimal passband loss. This local optimization of quality factors reduces insertion loss in the passband while maintaining effective signal separation.
2Reliability
If conventional band-stop filter designs are used, then the filter can block noise spectrum, but the transition band is wide and roll-off coefficient is poor
Solution Approach 1:
The filter uses multiple resonant circuits operating at different frequencies to create multiple stopbands. This segmentation enables narrow transition bands between passband and stopband by concentrating the suppression function in specific frequency regions, improving roll-off coefficient and spectral suppression precision.
Solution Approach 2:
The filter employs different resonant frequencies and quality factors for series and parallel resonant circuits. By carefully selecting these parameters, the transition band width is minimized while maintaining effective spectral suppression. The series resonant circuits provide narrow stopbands with steep roll-off characteristics.
3Measurement precision
If closely spaced radio frequency signals need to be separated, then band-stop filter is required, but existing filters have poor separation performance
Solution Approach 1:
Series resonant circuits are designed with high quality factors to create narrow, deep stopbands that precisely target specific frequency ranges. This local optimization of quality factor enables high-precision separation of closely spaced signals by creating sharp frequency selectivity at critical transition points.
Solution Approach 2:
The filter uses different resonant frequencies for series and parallel resonant circuits to create asymmetric frequency response characteristics. This parameter differentiation enables precise control over transition band width and stopband depth, improving signal separation precision for closely spaced frequencies while maintaining overall filter reliability.
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 reduced insertion loss and narrower transition bands, effectively separating closely spaced radio frequency signals with improved spectral suppression.
Implementation Method 1
a series resonance circuit and a series impedance element connected in series with each other, wherein the series resonance circuit includes a series resonator; and a parallel resonance circuit and a parallel impedance element connected in series with each other, wherein the parallel resonance circuit includes a parallel resonator
Data Source
AI summary
A filter circuit, a filter and a communication device relate to the technical field of communication. The filter circuit includes a series branch connected between the first port and the second port and including a series resonance circuit and a series impedance element connected in series with each other, wherein the series resonance circuit includes a series resonator; and a parallel branch connected between a parallel node and a ground potential and including a parallel resonance circuit and a parallel impedance element connected in series with each other, wherein the parallel resonance circuit includes a parallel resonator, and the parallel node is located on a connection path of the first port and the second port; wherein the resonance frequency of the series resonator is less than the resonance frequency of the parallel resonator.