Stubbed Differential Trace Pair Crosstalk Cancellation

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Solution Overview

Problem

As high-speed transmission in information handling systems increases, crosstalk between adjacent differential trace pairs becomes a significant issue, particularly in densely packed circuit boards, leading to signal integrity compromise and increased costs due to the need for wider spacing or more layers.

Innovation Solution

The implementation of trace stubs on differential trace pairs, configured to extend in a spaced apart orientation from one trace to another, reduces crosstalk by introducing secondary crosstalk that negates primary crosstalk, allowing for closer spacing without increasing total crosstalk, thereby enabling denser circuit boards with fewer layers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If differential trace pairs are spaced closer together to increase circuit board density, then circuit board density improves, but crosstalk between adjacent differential trace pairs increases

Engineering Contradiction:

Improvecircuit board densityVSAvoidcrosstalk

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The patent introduces stub structures on adjacent differential trace pairs that generate secondary crosstalk signals. These secondary crosstalk signals are deliberately designed to cancel out the primary harmful crosstalk through destructive interference, thereby converting the harmful crosstalk effect into a beneficial cancellation mechanism that enables closer trace spacing

Inventive Principle:

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

Solution Approach 2:

The patent modifies the electrical parameters of the trace pairs by adding stub structures with specific lengths and positions. These stubs change the impedance characteristics and signal timing of adjacent traces, enabling the crosstalk cancellation effect while maintaining high-speed signal transmission capabilities

Inventive Principle:

Principle #35Parameter changes

2Object-generated harmful factors

If differential trace pairs are spaced farther apart to reduce crosstalk, then crosstalk reduces, but circuit board density decreases and cost increases

Engineering Contradiction:

ImprovecrosstalkVSAvoidcircuit board density

Core Design Contradiction:

Object-generated harmful factorsVSQuantity of substance

Solution Approach 1:

Instead of simply increasing spacing to reduce crosstalk, the patent uses stub structures to generate beneficial secondary crosstalk that actively cancels harmful primary crosstalk. This allows maintaining high circuit board density while achieving effective crosstalk reduction through the cancellation mechanism

Inventive Principle:

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

3Object-generated harmful factors

If stripline structures are used to reduce crosstalk, then crosstalk reduces, but the number of signal layers increases and circuit board cost increases

Engineering Contradiction:

ImprovecrosstalkVSAvoidnumber of signal layers

Core Design Contradiction:

Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The patent segments the trace structure by adding stub elements to existing microstrip or stripline configurations. This segmentation allows the stubs to generate localized secondary crosstalk fields that cancel primary crosstalk, achieving effective crosstalk reduction without requiring conversion to multi-layer stripline structures

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent modifies the electrical parameters of existing trace structures by introducing stubs with specific dimensional parameters. These parameter changes enable effective crosstalk cancellation while maintaining the original trace structure type and layer configuration, avoiding increased device complexity

Inventive Principle:

Principle #35Parameter changes

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 configuration significantly reduces crosstalk, allowing for closer trace pair spacing without compromising signal integrity, enabling denser and cost-effective circuit board designs while maintaining high-speed transmission capabilities up to 100 GHz.

Implementation Method 1

The trace stubs operate to reduce crosstalk that is generated by high speed transmission of signals through the differential trace pairs by introducing a secondary crosstalk that cancels a primary crosstalk

Methodology Applied

Scientific EffectCrosstalk cancellation through secondary signal generation: Interference

Data Source

PatentUS10499492B2Stubbed differential trace pair system

Publication Date: 2019.12.03 DELL PROD LP

AI summary

A stubbed differential trace pair system includes a circuit board having a first differential trace pair with a first trace and a second trace, and a second differential trace pair with a third trace and a fourth trace, where the first trace located opposite the second trace and the third trace from the fourth trace. Second trace stubs extend in a spaced apart orientation relative to each other and from a side of the second trace that is opposite the second trace from the first trace. Third trace stubs extend in a spaced apart orientation relative to each other and from a side of the third trace that is opposite the third trace from the fourth trace. The second trace stubs and the third trace stubs are configured to reduce crosstalk generated by the transmission of signals through the first differential trace pair and the second differential trace pair.