Controlled-Impedance Cable Termination with Expansion Compensation
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Solution Overview
Problem
Controlled-impedance cable terminations face challenges with impedance mismatches due to cable expansion and contraction, leading to high-frequency attenuation and difficulty in maintaining consistent electrical length, especially during thermal excursions and flexure, which affects the precision and density of connections.
Innovation Solution
The use of compliant electrical contacts and an expansion/contraction compensator (ECC) with a ferrule and conductive center pin, along with optional conductive ground contacts, to maintain impedance control and accommodate cable expansion and contraction, ensuring consistent electrical connections across flexure and thermal cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional connectors are used to terminate controlled-impedance cables, then the cable can be connected to electrical devices, but impedance mismatches occur causing high-frequency attenuation
Solution Approach 1:
The patent changes the physical parameters of the connector components (center conductor diameter, insulation thickness, shield configuration) to match the cable's characteristic impedance. By carefully controlling these dimensional parameters, the connector maintains the same impedance as the cable, preventing reflections and high-frequency attenuation.
Solution Approach 2:
The patent applies different material properties and structural characteristics to specific local regions of the connector. The center conductor uses highly conductive material, the insulation has specific dielectric properties, and the shield provides electromagnetic containment. Each local region is optimized to maintain overall impedance continuity.
2Reliability
If cables are terminated with fixed rigid contacts, then electrical connection is established, but cable expansion and contraction due to temperature and flexure causes impedance variations
Solution Approach 1:
The patent replaces rigid fixed contacts with compliant dynamic contacts that can move and deform. The spring-loaded center contact and flexible shield segments allow the connector to adapt to cable expansion and contraction while maintaining continuous electrical connection and consistent impedance throughout thermal and mechanical cycles.
Solution Approach 2:
The patent uses flexible materials such as spring contacts, bellows structures, and flexible circuit boards in the connector design. These flexible elements accommodate cable movement and dimensional changes due to temperature and flexure, maintaining mechanical and electrical continuity without compromising impedance consistency.
3Ease of manufacture
If through holes are used in PCB for cable mounting, then cable termination is achieved, but PCB area is substantially increased decreasing connection density
Solution Approach 1:
The patent employs a compact connector design where components are nested within each other. The center conductor is surrounded by insulation, which is surrounded by the shield, with all elements tightly integrated. This nested structure minimizes the overall footprint of the connector on the PCB, allowing higher connection density.
Solution Approach 2:
The patent designs a universal connector structure that can terminate multiple cables or signal types using a standardized interface. The same basic connector design can accommodate different cable configurations and be mounted on various PCB layouts, reducing the need for specialized large-area terminations for each application.
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
This solution minimizes impedance mismatches and maintains precise impedance matching, enhancing the usability of controlled-impedance cables in high-frequency applications by accommodating cable expansion and contraction, thereby improving connection density and reliability.
Implementation Method 1
Another issue with termination of coaxial cables is the expansion and contraction of the signal conductor and/or the insulator due to temperature excursions and/or cable flexure over time.
Implementation Method 2
The ECC has a number of embodiments. Each embodiment includes an electrically-conductive ferrule with a bore.
Implementation Method 3
The terminator of the present invention employs compliant electrical contacts 12, 14 and an expansion/contraction compensator (ECC) 16 to provide an interface between the controlled-impedance cable and another device.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A controlled-impedance cable terminator (10) that minimizes the effects of cable expansion and contraction on impedance matching. The terminator (10) has an anchor block (18), an expansion/contraction compensator (ECC) (16) attached to the cable (40), a compliant signal contact (12) for making the electrical connection between the cable center conductor (42) and the electrical device (2). The ECC (16) has an electrically-conductive ferrule (62) with a bore (64). The ferrule bore (190) may be formed in the anchor block (18) instead of in a separate ferrule (38). The cable shield (46) is attached at the bore (64). A solid dielectric insert (74) fits into the ferrule bore (64). An electrically-conductive center pin (78) fits into a bore (76) in the dielectric insert (74) and has a bore (80) that accepts the center conductor (42) such that the center conductor (42) can expand and contracting while maintaining electrical contact with the center pin (78). A plate (20) abuts the anchor block face (34) and holds the compliant contacts (12, 14) in through apertures (352).