Cable Termination Structure With Individual Ground Paths
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Solution Overview
Problem
Existing cable termination methods often result in non-uniformities that lead to changes in impedance and mode conversion, reducing signal integrity due to insertion loss and crosstalk.
Innovation Solution
A conductive structure with tabs that wrap around cables to establish individual ground paths for each cable, providing low crosstalk and maintaining signal integrity by minimizing impedance discontinuities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional cable termination methods are used, then the cable can be connected to the connector, but non-uniformities are created that cause impedance changes and mode conversion, reducing signal integrity
Solution Approach 1:
The cable assembly is divided into distinct functional segments: the cable portion with uniform characteristics, the transition region with the conductive structure and tabs, and the connector portion. This segmentation allows each segment to be optimized independently - the cable for signal transmission and the transition region for impedance management - thereby maintaining signal integrity while accommodating the termination connection.
Solution Approach 2:
The conductive structure with tabs is applied locally at the cable termination point rather than along the entire cable length. This localized approach addresses the impedance discontinuity problem only where it occurs (at the termination) while preserving the uniform impedance characteristics of the cable body, thus maintaining signal integrity without unnecessary modifications elsewhere.
2Reliability
If the cable is made flexible to maintain uniform properties during routing, then signal integrity is preserved, but the cable becomes more susceptible to impedance changes at termination points
Solution Approach 1:
The conductive structure with tabs serves as an intermediary element between the flexible cable and the rigid connector. It mediates the transition by providing a gradual impedance transition path, allowing the flexible cable to maintain its uniform properties while the tabs manage the impedance discontinuity at the termination point, thus preserving signal integrity without requiring complex termination mechanisms.
3Area of stationary object
If multiple cables are routed together in a bundle, then space is saved, but crosstalk between cables increases
Solution Approach 1:
The conductive structure with tabs creates equipotential regions around each cable at the termination point. By providing a common reference potential through the conductive tabs and ground connections, the electromagnetic fields of adjacent cables are better controlled, reducing the coupling between cables and thus minimizing crosstalk while allowing the cables to be routed closely together in a compact bundle.
Data Source
AI summary
A cable assembly comprising a connector with a termination that enables high density and high signal integrity. Shields of cables are terminated to a paddle card via a conductive structure attached to a surface of the paddle card. The signal conductors of the cables are terminated to pads on the paddle card that are exposed within openings of the conductive structure. Such a structure creates a ground structure per cable that provides low insertion loss and low crosstalk, even when multiple cables are aligned side by side and terminated in one or more rows. The cables may be drainless, enabling a large number of cables, such as eight cables, to be packed within the width of a paddle card specified in high density standards such as QSFP-DD or OSFP. The cables may nonetheless have large diameter signal conductors, enabling 2.5 or 3 meter assemblies with less than 17 dB insertion loss.