Contraflow Interconnect Minimizes Crosstalk in On-Chip Networks

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Solution Overview

Problem

On-chip communication networks face significant challenges due to crosstalk between closely packed wires, which limits data transmission distance and area efficiency, and shielding methods increase network area.

Innovation Solution

A contraflow interconnect system where two sets of data connections are interlaced such that each wire transports data in the opposite direction of its neighbors, minimizing crosstalk and avoiding the need for shielding, thereby enhancing data transmission throughput and distance while reducing area consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If wires are packed closely together to minimize area, then area efficiency is improved, but crosstalk between neighboring wires increases

Engineering Contradiction:

Improveon-chip areaVSAvoidcrosstalk

Core Design Contradiction:

Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent inverts the conventional unidirectional data flow by implementing contraflow interconnect where adjacent wires transmit data in opposite directions. This inversion causes simultaneous switching of neighboring wires to occur in opposite phases, which minimizes crosstalk by ensuring that when one wire experiences a rising edge, its neighbor experiences a falling edge, thereby reducing capacitive coupling effects.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the direction parameter of data transmission on adjacent wires from being uniform (same direction) to alternating (opposite directions). This parameter change in transmission direction fundamentally alters the switching behavior of neighboring wires, transforming the crosstalk pattern from cumulative to canceling, thus reducing overall crosstalk impact while maintaining close wire packing.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If shielding is added to cancel crosstalk, then crosstalk is reduced, but area of the communication network increases greatly

Engineering Contradiction:

ImprovecrosstalkVSAvoidcommunication network area

Core Design Contradiction:

Object-affected harmful factorsVSArea of stationary object

Solution Approach 1:

The patent converts the harmful effect of capacitive coupling between neighboring wires into a beneficial effect by exploiting simultaneous switching in opposite directions. The coupling that would normally cause crosstalk now helps to cancel noise because adjacent wires switch in opposite phases, making the coupling effect beneficial rather than harmful and eliminating the need for additional shielding structures.

Inventive Principle:

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

3Length of stationary object

If data transmission distance is increased, then connectivity is improved, but crosstalk becomes progressively worse

Engineering Contradiction:

Improvedata transmission distanceVSAvoidcrosstalk

Core Design Contradiction:

Length of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent applies contraflow interconnect where adjacent wires transmit in opposite directions, causing simultaneous switching to occur in opposite phases along the transmission line. This inversion of switching phases reduces cumulative crosstalk effect over distance, allowing data to be transmitted reliably over longer distances without the crosstalk degradation that plagues conventional unidirectional interconnects.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS8935559B2System and method for reducing crosstalk in on-chip networks using a contraflow interconnect and offset repeaters

Publication Date: 2015.01.13 NVIDIA CORP

AI summary

A data connector includes two different sets of wires that transport data between components of a computer system. A first set of wires transports data from a first component to a second component. A second set of wires transports data from the second component to the first component. The first set of wires is interlaced with the second set of wires so that each wire in the data connector transports data in the opposite direction of one or more neighboring wires.