Wideband High Current RF Choke Network Resonance Neutralization
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Solution Overview
Problem
Current high current RF chokes used in CATV networks resonate at frequencies just above 1 GHz, limiting their operating frequency to about 1 GHz, and existing methods for frequency bandwidth extension, such as using low pass filters with diplexers, are complex and expensive.
Innovation Solution
A wideband high current RF choke arrangement is achieved by combining existing high current RF chokes with an all-pass T-bridge type filter, which eliminates resonance issues by neutralizing parasitic capacitance, extending the operating frequency range from 5 MHz to 1 GHz up to 3 GHz with a substantially flat response curve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high current RF chokes are used in CATV networks, then high alternating current can pass through, but resonance at frequencies above 1 GHz limits the operating frequency range
Solution Approach 1:
An all-pass filter is introduced as an intermediary component between the RF choke and the network. This filter has a transfer function designed to compensate for the resonance effect of the RF choke at frequencies above 1 GHz, thereby extending the usable frequency range while maintaining signal integrity
Solution Approach 2:
The patent modifies the frequency response characteristics by changing the parameters of the all-pass filter to match and counteract the resonance parameters of the RF choke. This parameter matching allows the system to operate effectively beyond the natural resonance frequency of the choke
2Reliability
If low pass filters with diplexers are used to block RF signals above 1 GHz, then frequency bandwidth extension is achieved, but system complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the need for complex diplexer systems by using a simpler all-pass filter configuration. This approach removes unnecessary components while achieving the same frequency bandwidth extension goal
Solution Approach 2:
The all-pass filter provides a cost-effective alternative to expensive diplexer systems. By using a simpler, more economical filter design, the patent achieves frequency extension without the high costs associated with complex diplexer assemblies
3Reliability
If sophisticated wounding of copper wire on ferrite core is used, then working frequency range is extended up to 1.4 GHz, but manufacturing complexity increases
Solution Approach 1:
The patent segments the frequency extension function into two separate components: the existing RF choke handles the base frequency range, while the all-pass filter extends the range to 3 GHz. This segmentation allows each component to be manufactured using standard, well-established techniques without requiring sophisticated custom winding processes
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 solution provides a wideband frequency extension with minimal transmission and reflection losses across the extended range, reducing the need for complex and costly diplexer systems and maintaining a flat response curve, thus enhancing the operational frequency range of RF chokes in CATV networks.
Implementation Method 1
which eliminates resonance issues by neutralizing parasitic capacitance
Data Source
AI summary
A high current RF choke network comprising a high current RF choke combined with an all-pass T-bridge filter. The high current RF choke may be connected to a grounded capacitor in the serial branch of the all-pass filter. In this case the parasitic capacitance of the RF choke practically becomes an integral part of the all-pass filter capacitor. The added capacitance in parallel to the parasitic capacitance of the high current RF choke practically neutralizes the resonances of the high current RF choke and thus extends significantly the operating frequency range of the network. The operating frequencies bandwidth range of the high current RF choke network is extended from the legacy range of 5 MHz to 1 GHz up to an extended range of at least 5 MHz to 3 GHz.