USB 2.0 DC Loss Compensation via Transition-Triggered Current Injection
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Solution Overview
Problem
USB 2.0 systems experience direct current (DC) loss due to additional components like USB cables and PCB traces, leading to signal failure in eye diagram compliance tests, and conventional hubs are intrusive, power-hungry, and uni-directional, failing to support USB On-The-Go and Embedded Host Supplement specifications.
Innovation Solution
A DC loss compensation circuit that detects transition periods in USB 2.0 systems and injects current during non-transition periods to boost the DC level of signals, maintaining signal integrity and supporting bidirectional communication, thus enabling compliance with USB On-The-Go and Embedded Host Supplement specifications without breaking transmission lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If additional components (USB cable, PCB trace, signal switches) are introduced in USB 2.0 systems, then system functionality and adaptability are improved, but DC loss increases and eye height shrinks
Solution Approach 1:
The patent creates a virtual copy of the host or device functionality through software-based USB On-The-Go and Embedded Host Supplement support, eliminating the need for physical hub infrastructure. This software copying approach maintains full USB functionality while avoiding the DC loss introduced by additional physical components.
2Reliability
If USB 2.0 hubs are used to repeat signals, then signal integrity is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent extracts the signal repeating function from a separate physical hub device and integrates it directly into the host or device controller. This extraction eliminates the need for external hub infrastructure, reducing device complexity and power consumption while maintaining signal integrity through direct controller-based signal management.
Solution Approach 2:
The patent merges the hub functionality with the host or device controller into a single integrated unit. By combining these functions, the system eliminates the need for separate hub hardware, reducing overall device complexity and power consumption while maintaining signal integrity through unified control.
3Reliability
If conventional USB 2.0 hubs are used, then signal repetition is achieved, but bidirectional communication support is lost
Solution Approach 1:
The patent implements dynamic role assignment where the host and device can interchange roles through software control. This dynamic switching capability enables bidirectional communication support for USB On-The-Go and Embedded Host Supplement specifications, allowing either endpoint to act as host or device as needed, while maintaining signal repetition functionality through the integrated controller.
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 a simple, power-efficient, and direction-agnostic method to maintain signal integrity across USB 2.0 systems, ensuring compliance with eye diagram tests and supporting bidirectional communication, making it compatible with a wide range of USB 2.0 applications.
Implementation Method 1
A current is injected into the 'high' level signal during the non-transition period so as to raise the DC level of the 'high' signal
Data Source
AI summary
In one embodiment, a current source is coupled to a channel input of a switch, and an output of the switch is coupled to a positive or negative data line in a USB 2.0 communication system. In addition, a first input of the voltage threshold comparator is coupled to the negative data line, a second input of the voltage threshold comparator is coupled to a positive data line, and an output of the voltage threshold comparator is coupled to a control input of the switch.