Cable Assembly Grounding for Signal Symmetry
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Solution Overview
Problem
Existing cable assemblies for high-speed signal transmission suffer from a significant conversion of differential-mode signals to common-mode signals due to impedance discontinuities and noise interference, affecting signal quality.
Innovation Solution
A cable assembly design featuring a printed circuit board (PCB) with signal conductive pads positioned between grounding pads, where each pair of signal conductors is connected to corresponding pads, and a grounding conductor connected to both sides of the signal pads, ensuring balanced signal symmetry and preventing common-mode signal conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If grounding conductor is soldered to only one grounding pad, then manufacturing is simpler, but signal symmetry is unbalanced causing differential-mode to common-mode conversion
Solution Approach 1:
The grounding conductor is designed with asymmetric routing that intentionally connects to both grounding pads on opposite sides of the signal conductors, creating a symmetric grounding potential that balances the differential signal paths and prevents common-mode conversion
Solution Approach 2:
By connecting the grounding conductor to both grounding pads, the invention creates an equipotential reference plane that equalizes the potential difference between the two signal conductors, maintaining balanced differential-mode signals and preventing conversion to common-mode signals
2Manufacturing precision
If signal pads are arranged without intervention by grounding pads, then PCB layout is simpler, but impedance discontinuities cause signal degradation
Solution Approach 1:
The pad arrangement is segmented into alternating signal and grounding pads, creating distinct functional zones that maintain controlled impedance by placing grounding references at regular intervals between signal pairs
Solution Approach 2:
Grounding pads are positioned as intermediary elements between signal pads, acting as impedance reference points that maintain consistent differential impedance and prevent signal degradation through controlled transitions
Data Source
AI summary
A cable assembly comprises: a metallic housing; a PCB received into the metallic housing. The PCB defines a plurality of grounding conductive pads and a plurality of pairs of signal conductive pads formed on a rear end thereof. Each pair of signal conductive pads are intervened between two grounding conductive pads. And a cable having a plurality of wires are electrically connected with the PCB. Wherein at least one wire of the plurality of wires comprises a pair of differential signal conductors electrically connected to a corresponding pair of signal conductive pads, and a grounding conductor electrically connected to two grounding conductive pads located at two sides of the pair of signal conductive pads.