LC Band-Pass Filter Topology for Dual-Side Attenuation Poles
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Solution Overview
Problem
Existing band pass filters with multiple LC resonators do not effectively provide attenuation poles near desired frequencies higher than the pass band, limiting their frequency characteristics.
Innovation Solution
A band pass filter configuration including a first and second LC resonator, a third inductor, and a third capacitor, where the third capacitor is connected between the second end of the third inductor and the node between the first and second LC resonators, allowing for the placement of attenuation poles near frequencies lower and higher than the pass band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional band pass filter with multiple LC resonators is used, then the pass band frequency characteristics are maintained, but attenuation poles cannot be provided near desired frequencies higher than the pass band
Solution Approach 1:
The filter is divided into multiple LC resonator stages (first, second, and third LC resonators) with distinct functions. The first and second LC resonators handle pass band signals, while the third LC resonator specifically provides attenuation poles near frequencies higher than the pass band. This segmentation allows each segment to be optimized for its specific function, resolving the contradiction between maintaining pass band characteristics and providing flexible attenuation pole placement.
Solution Approach 2:
The third LC resonator acts as an intermediary element that mediates between the main signal path (first and second LC resonators) and the ground. By introducing this intermediate component with specific inductance and capacitance values, the patent enables the formation of attenuation poles at desired frequencies higher than the pass band without disrupting the pass band characteristics maintained by the first two resonators.
2Reliability
If additional components are added to provide attenuation poles near frequencies higher than the pass band, then frequency characteristics are improved, but device complexity increases
Solution Approach 1:
Instead of redesigning the entire filter structure, the patent applies local quality by adding a third LC resonator with specific characteristics only where needed (near frequencies higher than the pass band). The first and second LC resonators maintain their original design for pass band signals, while the third resonator is locally configured with specific inductance L3 and capacitance C3 values to provide attenuation poles only in the higher frequency region, thus improving frequency characteristics without proportionally increasing overall complexity.
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 configuration enables the provision of attenuation poles at desired frequencies both below and above the pass band, improving the frequency characteristics of the band pass filter by adjusting impedance ratios and resonant frequencies.
Implementation Method 1
A band pass filter including a first LC resonator, a second LC resonator, a third inductor, and a third capacitor... allows attenuation poles to be provided near a desired frequency lower than the pass band of the band pass filter and a desired frequency higher than the pass band
Implementation Method 2
The third capacitor is electrically connected between a second end of the third inductor and a node between the first LC resonator and the second LC resonator... allowing for the placement of attenuation poles near frequencies lower and higher than the pass band
Data Source
AI summary
In a band pass filter, a signal input into a first terminal is transmitted to a first LC resonator and a second LC resonator in this order and is then output from a second terminal. The band pass filter includes a third inductor and a third capacitor. A first end of the third inductor is electrically connected to the ground. The third capacitor is electrically connected between a second end of the third inductor and a node between the first LC resonator and the second LC resonator.