PCB Reference Channel Layout for Low-Speed Noise Cancellation

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Solution Overview

Problem

Low-speed data communication interfaces in information handling systems are susceptible to common mode noise due to late design integration, which compromises signal integrity, as they are often routed in noisy areas of the PCB, unlike high-speed interfaces.

Innovation Solution

The implementation of a voltage reference generator and a closely coupled reference channel alongside the signal channel, adhering to similar routing guidelines, to cancel common mode noise by ensuring both channels experience similar noise conditions, thereby improving noise immunity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If low-speed data communication interfaces are routed in noisy areas of the PCB, then ease of routing is improved, but signal integrity deteriorates due to common mode noise susceptibility

Engineering Contradiction:

Improverouting easeVSAvoidsignal integrity

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

A reference channel is introduced as an intermediary element that couples the noise environment from noisy areas to the receiver's reference input. This mediator allows the receiver to measure and compensate for common mode noise, thereby maintaining signal integrity even when routed through noisy PCB areas.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The reference channel provides feedback about the noise conditions experienced by the signal channel. The receiver uses this feedback to adjust its noise cancellation, enabling dynamic compensation for common mode noise and improving signal integrity in noisy routing environments.

Inventive Principle:

Principle #23Feedback

2Reliability

If a reference channel is coupled adjacent to the signal channel, then noise immunity is improved through common mode noise cancellation, but device complexity increases

Engineering Contradiction:

Improvenoise immunityVSAvoidchannel configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The reference channel is merged with the signal channel by coupling them adjacent to each other on the PCB. This physical merging allows both channels to experience identical noise conditions, enabling effective common mode noise cancellation while minimizing the additional space and complexity required.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The reference channel serves multiple functions: it provides a noise reference for common mode rejection, maintains impedance matching, and enables the receiver to compensate for environmental noise. This multi-functionality justifies the added complexity by delivering significant noise immunity improvements.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS12495483B2Noise cancellation in low-speed signals

Publication Date: 2025.12.09 DELL PROD LP

AI summary

An information handling system includes a PCB, a transmitter for a data communication interface, a receiver for the data communication interface, a first channel instantiated in the printed circuit board, and a second channel instantiated in the printed circuit board. The receiver includes a first input and a second input. The first channel is coupled between an output of the transmitter and the first input of the receiver and is routed in a first path in the printed circuit board. The second channel is coupled to provide a reference voltage to the second input of the receiver and is routed in a second path in the printed circuit board. At least a portion of the second path is routed adjacent to a portion of the first path.