Reactance Filter Capacitor Topology for Intermodulation Suppression
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Solution Overview
Problem
Existing filter technologies face challenges in achieving effective suppression of intermodulation products and harmonics while maintaining a reasonable area requirement, as cascading resonators leads to saturation and increased space requirements, limiting their miniaturization and economic viability.
Innovation Solution
A filter circuit design that incorporates a series and parallel branch configuration with resonators and capacitors, where a capacitor is connected in series or parallel to the resonators to create a voltage or current divider, reducing the saturation effect and achieving broadband suppression of intermodulation products and harmonics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If multiple resonators are cascaded to suppress intermodulation products, then suppression effectiveness is improved, but the area required for the filter increases and saturation occurs
Solution Approach 1:
A capacitor is introduced as an intermediary element connected in parallel to at least one resonator in the cascade. This capacitor acts as a mediator that modifies the voltage distribution across the resonators, reducing the voltage stress on individual nonlinear components and thereby suppressing intermodulation products without requiring additional cascaded resonators that would increase the filter area.
Solution Approach 2:
The invention changes the electrical parameters of the filter by adding a capacitor with specific capacitance value in parallel to a resonator. This parameter modification alters the voltage division ratio in the cascade, optimizing the operating point of nonlinear components to reduce intermodulation distortion while maintaining the same physical footprint and avoiding saturation effects.
2Reliability
If voltage across nonlinear component is reduced to expand linear operating range, then linearity is improved, but suppression effectiveness of intermodulation products decreases
Solution Approach 1:
By adding a capacitor in parallel to a resonator, the voltage distribution parameters in the cascade are modified. The capacitor creates a voltage division effect that reduces the voltage across individual nonlinear resonators, expanding their linear operating range. Simultaneously, the overall cascade structure maintains sufficient voltage stress to achieve effective intermodulation suppression, resolving the contradiction between linearity and suppression effectiveness.
Solution Approach 2:
The capacitor serves as an intermediary that redistributes voltage across the cascade. It mediates between the need for reduced voltage (to improve linearity) and the need for sufficient voltage stress (to maintain suppression effectiveness). The capacitor's presence allows the system to achieve both goals simultaneously by optimizing the voltage division ratio.
3Object-affected harmful factors
If cascading degree is increased to suppress intermodulation products, then suppression effectiveness is improved, but saturation effect occurs and additional suppression becomes less effective
Solution Approach 1:
The capacitor acts as an intermediary that enhances the suppression effectiveness of each individual resonator in the cascade. By optimizing the voltage distribution, the capacitor ensures that each resonator operates in a more linear region, thereby increasing the suppression efficiency per resonator. This prevents the saturation effect where additional resonators yield diminishing returns, as each resonator now contributes more effectively to suppression.
Solution Approach 2:
The invention changes the operating parameters of the cascade by introducing a capacitor that modifies the voltage division ratio. This parameter change ensures that each resonator operates at an optimized voltage level, maximizing the suppression efficiency of each component. As a result, the system achieves effective intermodulation suppression without entering the saturation region where additional cascading becomes inefficient.
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 effectively reduces intermodulation products and harmonics with a moderate increase in resonator area, offering improved linearity and suppression efficiency while maintaining transmission behavior, albeit with a potential trade-off in bandwidth and VSWR.
Implementation Method 1
a capacitor connected in series or parallel to at least one resonator arranged in the series branch, in particular to at least one resonator arranged in the first parallel branch, resulting in a voltage or current division
Data Source
Figure 1A~1C
Figure 1D~1E
Figure 2~4
AI summary
The invention relates to improving the linearity of a reactance filter made from serial and parallel resonators in which a capacitor is connected, in series or parallel, either to a parallel resonator or a cascade of parallel resonators or to a series resonator or a cascade of series resonators.