USB Hub Galvanic Isolation Circuit for Jitter Reduction

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Solution Overview

Problem

Existing USB communication interfaces, particularly high-speed USB devices, face challenges with galvanic isolation due to increased jitter requirements and transmission lag, which are not adequately addressed by prior art devices like the Analog Devices AduM4160, especially in industrial environments prone to voltage spikes and ground loops.

Innovation Solution

Incorporating a galvanic isolator circuit module between the USB AFE circuit module and the hub core, utilizing components such as coupling capacitors, transformers, or photo-optical devices, and employing a serialized data interface like ULPI to reduce time delays and jitter while maintaining high-speed USB specifications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If galvanic isolation is incorporated into USB communication interface, then protection against voltage spikes and ground loops is improved, but transmission lag and jitter increase

Engineering Contradiction:

Improveprotection against voltage spikes and ground loopsVSAvoidtransmission lag and jitter

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent introduces an intermediary device (isolation barrier with controlled impedance) between the galvanic isolation component and the USB communication interface. This intermediary maintains signal integrity by providing a controlled impedance path that minimizes reflections and signal degradation, thereby reducing transmission lag and jitter while preserving the galvanic isolation protection against voltage spikes and ground loops.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs parameter changes by carefully selecting and adjusting the electrical characteristics of the isolation barrier, including impedance matching, capacitance values, and signal conditioning parameters. By optimizing these parameters, the system achieves minimal transmission lag and jitter while maintaining effective galvanic isolation for industrial environment protection.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If galvanic isolator circuit module is added between USB AFE and hub core, then isolation effectiveness is improved, but device complexity increases

Engineering Contradiction:

Improvegalvanic isolation effectivenessVSAvoidcircuit module complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the galvanic isolation functionality with the existing USB hub architecture by integrating the isolation circuit module into the hub's data path. This consolidation approach provides effective galvanic isolation between the USB AFE and hub core while avoiding the complexity of completely separate isolation systems, as the isolation functions are combined with the existing communication interface components.

Inventive Principle:

Principle #5Merging (Combining)

3Speed

If high-speed USB specifications are maintained with galvanic isolation, then data transmission speed is preserved, but component count and cost increase

Engineering Contradiction:

Improvedata transmission speedVSAvoidcomponent count

Core Design Contradiction:

SpeedVSQuantity of substance

Solution Approach 1:

The patent designs the isolation circuit module to serve multiple functions simultaneously: providing galvanic isolation, maintaining controlled impedance for high-speed signals, and supporting various USB speed modes (high-speed, super-speed). This multi-functional approach preserves data transmission speed while reducing the overall component count, as a single isolation module handles multiple requirements that would otherwise require separate components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

The solution provides effective galvanic isolation that meets high-speed USB transmission lag and jitter specifications, reducing costs and component counts, and ensuring reliable data transmission in industrial environments.

Implementation Method 1

Devices such as coupling capacitors, transformers, or photo-optical devices are commonly used for galvanic isolation

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

transformers

Methodology Applied

Scientific EffectElectromagnetic Induction: Electromagnetic Induction

Implementation Method 3

photo-optical devices

Methodology Applied

Scientific EffectPhoto-optical conversion: Photoelectric Effect

Data Source

PatentUS9785598B2USB hubs with galvanic isolation

Publication Date: 2017.10.10 MAXIM INTEGRATED PROD INC

AI summary

A universal serial bus (USB) hub includes a USB AFE circuit module, a hub core and an isolator circuit module interposed between the USB AFE circuit module and the hub core. Data communications between the hub core and the first USB AFE circuit module pass through the isolator circuit module. A method for communicating through a universal serial bus hub includes providing a USB AFE circuit module, providing a hub core, providing an isolator circuit module interposed between the USB AFE circuit module and the hub core, and directing communication from the USB AFE circuit module to the hub core through the isolator circuit module.