Shielded Cable Asymmetry for Signal Skew Compensation

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Solution Overview

Problem

Shielded electrical cables experience electrical skew due to voids created by the overlapping cable shield, which affects the dielectric constant and signal performance in differential pairs, leading to imbalance in signal transmission speeds.

Innovation Solution

The electrical cable design incorporates insulators with different dielectric constants for each conductor, and a cable shield wrapped around the conductor assembly, with a flap covering the inner edge to create a void closer to one conductor, compensating for the dielectric imbalance by adjusting the capacitance of the second conductor to match the first, thereby mitigating skew.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a cable shield is wrapped around the conductor assembly, then electromagnetic shielding is improved, but electrical skew is introduced due to voids at the shield overlap

Engineering Contradiction:

Improveelectromagnetic interferenceVSAvoidsignal balance

Core Design Contradiction:

Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The patent applies local quality by positioning the shield overlap void specifically closer to one conductor (first conductor) than the other (second conductor) in the differential pair. This asymmetric placement creates a localized dielectric constant change that compensates for the capacitance imbalance, allowing the shield to provide EMI protection while the controlled void mitigates signal skew.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the dielectric parameter (dielectric constant) by introducing an air void at a specific location within the cable structure. The void's position closer to one conductor changes the effective dielectric constant in that region, which adjusts the capacitance and signal propagation characteristics to compensate for skew caused by the shield overlap.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the cable shield overlaps itself to provide continuous shielding, then shielding effectiveness is improved, but a void is created that shifts the shield farther from the conductor and changes the dielectric constant

Engineering Contradiction:

Improveshielding continuityVSAvoiddielectric constant uniformity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent converts the harmful effect of the shield overlap void into a beneficial one. Instead of treating the void as a defect that disrupts shielding and uniformity, the invention positions the void strategically closer to one conductor to compensate for capacitance imbalance. The void's dielectric effect is harnessed to improve signal balance while the shield maintains its continuous overlapping structure for reliable EMI shielding.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Manufacturing precision

If the void is positioned closer to one conductor, then capacitance imbalance is compensated, but the shield structure becomes asymmetric

Engineering Contradiction:

Improvesignal balanceVSAvoidshield symmetry

Core Design Contradiction:

Manufacturing precisionVSShape

Solution Approach 1:

The patent deliberately introduces asymmetry into the otherwise symmetric cable structure by positioning the shield overlap void closer to one conductor than the other. This asymmetric void placement is intentional and functional, creating a localized dielectric constant change that compensates for capacitance imbalance in the differential pair, thereby improving signal balance despite the asymmetric appearance.

Inventive Principle:

Principle #4Asymmetry

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 design ensures balanced signal transmission speeds in differential pairs by proportionally decreasing the capacitance of the second conductor, effectively reducing skew and improving overall signal performance.

Implementation Method 1

a void is created that is filled with air, which has a different dielectric constant than the material of the insulator and shifts the cable shield farther from the signal conductor

Methodology Applied

Scientific EffectDielectric constant: Dielectric Permittivity

Implementation Method 2

The first insulator has an outer surface and a first effective dielectric constant. The second insulator has an outer surface and a second effective dielectric constant less than the first effective dielectric constant

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS20200118714A1Electrical cable

Publication Date: 2020.04.16 TE CONNECTIVITY SOLUTIONS GMBH

AI summary

An electrical cable includes a conductor assembly having a first conductor, a second conductor, a first insulator surrounding the first conductor and a second insulator surrounding the second conductor. The first insulator has a first thickness between the first conductor and an outer surface. The second insulator has a second thickness between the second conductor and an outer surface. The first thickness is greater than the second thickness. A cable shield is wrapped around the conductor assembly and engages the outer surface of the first insulator along a first segment and engaging the outer surface of the second insulator along a second segment. The cable shield has an inner edge and a flap covering the inner edge. The cable shield forms a void at the inner edge located closer to the first conductor than the second conductor.