Directional Coupler Assembly for High Isolation DOCSIS 3.1
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional directional couplers in cable television systems, such as those used in DOCSIS 3.1 Full Duplex operations, face challenges in achieving high enough signal isolation (above 40 dB) to support higher bit rates in both forward and reverse directions, as they typically provide only 20 to 30 dB of isolation.
Innovation Solution
A directional coupler assembly is designed with a directional coupler transformer and an impedance circuit that controls isolation between input and output signals by directing internal signals to a signal ground, allowing for high isolation (above 40 dB) without affecting the impedance at each port, enabling simultaneous bidirectional signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional directional couplers use a 2-hole ferrite core and bifilar magnet wires, then the device structure is simple, but the isolation is only 20 to 30 decibels which is insufficient for DOCSIS 3.1 Full Duplex operation
Solution Approach 1:
The directional coupler is divided into multiple functional sections: a first section with a first ferrite core and first bifilar magnet wires for initial signal coupling, and a second section with a second ferrite core and second bifilar magnet wires for additional coupling. This segmentation allows each section to contribute to the overall isolation, achieving 40 dB or more isolation while maintaining reasonable device complexity through modular design.
2Productivity
If higher isolation (40 dB or more) is achieved to support DOCSIS 3.1 Full Duplex operation, then signal bit rates in both directions can be increased, but the device complexity increases
Solution Approach 1:
Multiple directional coupler sections are merged into a single integrated device, where the first and second sections work together to provide cumulative isolation effect. The combined structure achieves 40 dB or more isolation necessary for high signal bit rates in DOCSIS 3.1 Full Duplex operation, while the merging of functions into one unified device prevents excessive complexity increase.
3Ease of operation
If conventional couplers provide 20 to 30 dB isolation, then the device complexity remains low, but the isolation is insufficient for full duplex operation with higher bit rates
Solution Approach 1:
Different sections of the directional coupler have different local characteristics optimized for their specific functions. The first section uses specific ferrite core and bifilar magnet wire configurations for initial coupling, while the second section uses different configurations to enhance isolation. This local quality differentiation allows the overall device to achieve 40 dB or more isolation while maintaining ease of operation through standardized modular sections.
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 achieves isolation of 40 dB or more, supporting higher bit rates in both directions and meeting DOCSIS 3.1 Full Duplex criteria, while maintaining common impedances at each port, thus enhancing data bandwidth and preventing signal interference.
Implementation Method 1
The directional coupler transformer may be configured to (i) receive a forward input signal from a first port of the plurality of ports, (ii) generate a coupled signal at a second port of the plurality of ports
Data Source
AI summary
An apparatus includes a plurality of ports, a directional coupler transformer and an impedance circuit. The directional coupler transformer may be configured to (i) receive a forward input signal from a first port of the plurality of ports, (ii) generate a coupled signal at a second port of the plurality of ports, (iii) generate a forward output signal and receive a return signal at a third port of the plurality of ports and (iv) generate an internal signal at an internal node. The impedance circuit may be directly connected to the internal node and configured to direct the internal signal to a signal ground to control an isolation between the forward input signal and the return input signal. The isolation is controlled by an impedance of the impedance circuit.