Bi-Directional Coupler Termination Switching for Low-Loss Isolation
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Solution Overview
Problem
In full duplex node designs, the use of two separate directional couplers for upstream and downstream connections in networks leads to increased insertion loss and reduced isolation due to imperfect termination at the isolating port, which affects the directivity and performance of the system, especially when one or both test points are not connected.
Innovation Solution
A bi-directional coupler system with switches that toggle between termination loads and test points, ensuring all ports are properly terminated even when test points are not connected, thereby maintaining maximum directivity and isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If two separate directional couplers are used for upstream and downstream connections, then isolation between upstream and downstream is improved, but insertion loss increases and device complexity increases
Solution Approach 1:
The patent combines two separate directional couplers into a single bi-directional coupler that handles both upstream and downstream connections. This merging reduces the total insertion loss from 2 dB (two couplers) to 1 dB (one coupler) while maintaining adequate isolation through proper port termination management.
Solution Approach 2:
The bi-directional coupler is designed to serve multiple functions: it handles both upstream and downstream signal directions, provides test point access for both directions, and maintains isolation between directions through dynamic termination switching. This multi-functionality eliminates the need for separate couplers while managing the trade-off between isolation and insertion loss.
2Object-affected harmful factors
If two separate directional couplers are used for upstream and downstream connections, then isolation between upstream and downstream is improved, but device complexity increases
Solution Approach 1:
The patent merges two separate directional couplers into a single bi-directional coupler unit. This reduces the component count from two couplers to one, simplifying the overall device architecture while managing isolation requirements through intelligent termination management at the coupler ports.
3Loss of energy
If a single bi-directional coupler is used for both upstream and downstream directions, then insertion loss is reduced, but isolation between upstream and downstream deteriorates when test points are not connected
Solution Approach 1:
The patent implements dynamic termination switching where switches automatically connect termination loads to unused test point ports. This dynamic adjustment ensures that when test points are not connected, the isolation between upstream and downstream directions is maintained at optimal levels, preventing the isolation deterioration that would otherwise occur with a static single coupler configuration.
Solution Approach 2:
The patent introduces switches and termination loads as intermediary components between the bi-directional coupler and the external environment. These intermediaries manage the coupling between the coupler ports and external test points, ensuring that when test points are disconnected, the termination loads maintain proper impedance matching and isolation without affecting the low insertion loss benefit of the single coupler design.
4Measurement precision
If termination loads are connected to all ports of the bi-directional coupler, then directivity and isolation are improved, but adaptability to different test configurations deteriorates
Solution Approach 1:
The patent employs dynamic switching mechanisms that automatically adjust the termination configuration based on test point connection status. When test points are connected, the switches disconnect the termination loads to allow signal passage; when test points are disconnected, the switches connect the termination loads to maintain directivity and isolation. This dynamic behavior resolves the contradiction between maintaining high measurement precision and providing test configuration flexibility.
Data Source
AI summary
In one embodiment, an apparatus includes a bi-directional coupler for coupling an upstream signal and a downstream signal to a termination load. A test point detection mechanism is configured to detect when a test point device is inserted in a test point connector. The test point device is configured to perform a test of the upstream signal or the downstream signal. A switch is configured to switch from being coupled to the termination load to being coupled to the test point device when the test point device is detected as being inserted in the test point connector. The switch is configured to switch from being coupled to being coupled to the test point device to the termination load when the test point device is detected as being removed from being inserted in the test point connector.