Band-Pass Filter Circuit With Transient Clamping and Stable Passband
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Solution Overview
Problem
Existing band pass filters with over-voltage protection often suffer from ineffective suppression of high-voltage transient energy within the operational frequency band, leading to potential damage to sensitive components, and they also experience unstable band pass characteristics due to parasitic capacitance from semi-conductor clamping components.
Innovation Solution
A band pass filter circuit design that includes a high pass filter and a low pass filter separated from each other, connected in series with the transmission line, along with a primary suppressor and supplemental suppressors to effectively clamp high-voltage transients, while minimizing the impact of parasitic capacitance through strategic pairing with shunt capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If semi-conductor clamping components are used for over-voltage protection, then suppression of high-voltage transients is improved, but band pass characteristics become unstable due to parasitic capacitance
Solution Approach 1:
The patent extracts the harmful parasitic capacitance effect by separating the suppression function from the band pass filter components. The suppressor is connected to ground through a dedicated path, isolating its parasitic capacitance from the filter's signal path, thus removing the destabilizing influence while maintaining protection.
Solution Approach 2:
The patent introduces a ground connection as an intermediary element. The suppressor clamps transients to ground potential rather than directly affecting the filter components. This intermediary ground path absorbs the parasitic capacitance effects, preventing them from destabilizing the band pass characteristics.
2Speed
If gas discharge tube is used as suppressor, then response speed to transients is improved, but firing voltage overshoot increases causing damage to sensitive components
Solution Approach 1:
The patent applies prior cushioning by providing a controlled impedance path to ground for the gas discharge tube. This pre-established path limits the rate of voltage rise during firing, cushioning the overshoot effect before it can damage sensitive components downstream.
Solution Approach 2:
The patent introduces the transmission line characteristic impedance as an intermediary between the gas discharge tube and the load. This impedance mediator controls the current surge and voltage overshoot during GDT firing, protecting sensitive components while allowing fast response.
3Reliability
If high pass filter and low pass filter are separated and connected in series, then over-voltage suppression is improved, but device complexity increases
Solution Approach 1:
The patent applies multi-functionality by designing the series connection of high pass and low pass filters to serve dual purposes: signal band pass filtering and over-voltage suppression. The same structural elements that provide filtering also contribute to transient suppression when properly terminated, eliminating the need for separate protection 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
The design achieves reliable over-voltage suppression while maintaining stable band pass characteristics, effectively protecting voltage-sensitive components from high-voltage transients and ensuring efficient transmission of electromagnetic signals with minimal loss and distortion.
Implementation Method 1
a high pass filter for blocking transmission to the output terminal of electromagnetic signals received by the transmission line that fall below the operational frequency band
Implementation Method 2
a low pass filter for blocking transmission to the output terminal of electromagnetic signals received by the transmission line that fall above the operational frequency band
Implementation Method 3
a primary suppressor for clamping high-voltage, transient electromagnetic energy received by the transmission line
Implementation Method 4
a set of supplemental suppressors for clamping high-voltage, transient electromagnetic energy received by the transmission line
Data Source
AI summary
A band pass filter circuit for transmitting electromagnetic signals within a desired frequency band includes a transmission line extending between input and output terminals, a high pass filter connected to the transmission line for blocking the transmission of signals falling below the operational frequency band, and a low pass filter connected to the transmission line for blocking the transmission of signals falling above the operational frequency band. Additionally, a primary suppressor connects the transmission line to ground and suppresses unwanted transients on the transmission line. A set of supplemental suppressors connects the transmission line to ground and suppresses any residual transient energy on the transmission line after treatment by the primary suppressor. Each supplemental suppressor is paired in parallel with a higher-valued capacitor from the low pass filter in order to minimize the effect of its parasitic capacitance on the band pass characteristics of the circuit.