Ground Bus Shielding Structure for Cable Card Signal Integrity
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Solution Overview
Problem
Signal integrity and electrical performance of electrical connectors are negatively impacted at the interface between cables and circuit cards due to exposure of signal conductors, changes in spacing between signal conductors, and changes in shielding, which affect signal integrity.
Innovation Solution
A cable card assembly with a ground bus that includes an inner and outer bus member, ground blades, and a contact assembly to provide electrical shielding and maintain target impedance along signal paths, connected to both the cable shields and the circuit card's ground plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If signal conductors are exposed and transition from cable to circuit card, then connection is established, but signal integrity deteriorates due to air exposure and spacing changes
Solution Approach 1:
The patent introduces an intermediary shielding structure (ground bus with inner and outer bus members) that mediates between the exposed signal conductors and the harmful air exposure environment. This shielding structure maintains controlled impedance by providing a consistent reference plane, eliminating the harmful effect of air exposure while allowing the signal transition to occur.
Solution Approach 2:
The patent creates an inert electromagnetic environment by enclosing the signal conductors within a controlled shielding structure during the transition zone. The ground bus forms a shielded cavity that replaces the harmful air exposure with a controlled electromagnetic environment, maintaining signal integrity through consistent impedance characteristics.
2Device complexity
If cable shields are disconnected at the interface, then cable assembly is simplified, but electromagnetic shielding effectiveness decreases
Solution Approach 1:
The patent merges the cable shield function with the ground bus shielding structure. The cable shield is continuously connected to the ground bus, combining the cable's inherent shielding with the connector's shielding structure. This integration maintains electromagnetic shielding effectiveness while avoiding the complexity of separate shield management systems.
Solution Approach 2:
The ground bus serves multiple functions: it provides the reference plane for controlled impedance, acts as a shield against electromagnetic interference, and provides a mechanical mounting structure. This multi-functionality maintains shielding effectiveness while simplifying the overall assembly by eliminating the need for separate shield components.
3Ease of operation
If spacing between signal conductors changes during transition, then physical connection is achieved, but signal integrity is affected
Solution Approach 1:
The patent carefully controls the geometric parameters of the shielding structure and signal conductor arrangement during the transition zone. By maintaining consistent spacing and positioning parameters within the shielded environment, the controlled impedance is preserved despite the physical transition from cable to circuit card, ensuring signal integrity while achieving proper connection.
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
Enhances electrical performance by reducing crosstalk and maintaining signal integrity through improved shielding and controlled impedance, thereby improving the connection interface with circuit cards.
Implementation Method 1
The ground bus is electrically connected to the cable shields to electrically connect the cable shields of the cables. The ground bus is electrically connected to the ground plane of the circuit card. The inner bus member is configured to be positioned between the cables and the circuit card and provides shielding around portions of the cables.
Implementation Method 2
maintaining target impedance along signal paths
Data Source
AI summary
A cable card assembly includes a circuit card having conductors and a contact assembly coupled to the circuit card and cables. The contact assembly includes a contact holder holding signal contacts and a ground bus separate and discrete from the contact assembly. The ground bus is electrically connected to cable shields to electrically connect the cable shields to the ground plane of the circuit card. The ground bus includes a shell having an inner bus member and an outer bus member. The ground bus includes ground blades received in the shell and located between the corresponding cables. The ground blades are electrically connected to the inner bus member and the outer bus member.