Ground Shield for Circuit Board Termination Crosstalk
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Solution Overview
Problem
Conventional cable interconnection systems experience increased crosstalk and impedance discontinuities at termination ends due to the lack of a ground plane, particularly in high-speed data transmission applications where differential signal wires are used.
Innovation Solution
A cable assembly with a conductive metal ground plate extending from the circuit board to fill the gap between wire pairs, providing a ground plane and reducing crosstalk, along with mounting arms for attachment and strain relief.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the outer shields of cable wires are removed to facilitate attachment to circuit card, then ease of manufacture is improved, but crosstalk between cable wires increases
Solution Approach 1:
A ground plate is introduced as an intermediary element between the cable wires and the circuit board. The ground plate extends beneath the stripped cable wires and connects to ground on the circuit board, providing a reference potential and shielding effect that reduces crosstalk while allowing the wires to be properly attached to the circuit board
2Ease of manufacture
If the cable wire outer shield is peeled back to expose conductors for termination, then ease of manufacture is improved, but impedance discontinuity increases
Solution Approach 1:
The ground plate serves as a mediator that bridges the gap created by peeling back the outer shield. By extending the ground reference into the previously ungrounded area, it maintains a consistent reference potential that helps preserve impedance continuity throughout the termination region
3Reliability
If grounding is extended behind the circuit board to reduce crosstalk, then signal quality is improved, but device complexity increases
Solution Approach 1:
The ground plate is designed to perform multiple functions simultaneously: it provides extended grounding behind the circuit board to reduce crosstalk, serves as a mounting structure for attaching the cable assembly to the circuit board, and acts as a shield to maintain impedance continuity. This multi-functionality reduces the need for separate components
Data Source
AI summary
A cable-circuit board assembly is disclosed for use in providing a high speed transmission line for connecting electronic devices together. The circuit board is joined to a ground extension member that extends rearwardly of the circuit board and between sets of wires that are terminated to respective surfaces of the circuit board. The extension portion places a ground plane in the termination area of the connector, rear of the trailing edge of the circuit board to provide shielding between pairs of wires on opposite sides of the paddle card where the cable shields are cut back.