Optical USB Isolator Using Digital Packet Translation
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Solution Overview
Problem
Conventional USB repeaters rely on timing information from eUSB2 devices for electrical isolation, limiting their ability to support full-speed communications and increasing complexity and cost, as they lack accurate clock hardware necessary for detecting extended idle states and managing high-speed bus state transitions.
Innovation Solution
The implementation of isolating eUSB2 repeaters that use non-crystal oscillators and alternative mechanisms for timing functions, allowing them to translate EOP signals and manage bus state changes without relying on eUSB2 control messages or accurate clocks, enabling electrical isolation between USB2 devices without the need for clock hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional repeater components are used to provide electrical isolation, then effective electrical isolation is achieved, but device complexity and cost increase due to complex implementations required to translate between packetized digital information and analog signals
Solution Approach 1:
The patent replaces conventional analog signal translation mechanisms with a digital packet-based communication system. Instead of using complex analog-to-digital converters and timing recovery circuits, the invention uses simple digital packets to convey USB data across the isolation barrier, dramatically reducing device complexity while maintaining electrical isolation.
Solution Approach 2:
The invention changes the fundamental parameter of signal representation from continuous analog waveforms to discrete digital packets. This parameter change eliminates the need for complex timing synchronization and analog signal processing, reducing both device complexity and cost while preserving electrical isolation functionality.
2Reliability
If conventional repeater components are used to provide electrical isolation, then effective electrical isolation is achieved, but the bandwidth of the USB connection is limited to full speed (12 Mbps)
Solution Approach 1:
The patent replaces the analog signaling mechanism with digital packet-based communication, enabling support for USB 2.0 high-speed mode (480 Mbps). The packet-based approach eliminates bandwidth limitations inherent in analog translation systems, allowing the isolation device to support full USB 2.0 speed ranges while maintaining electrical isolation.
3Measurement precision
If accurate clock hardware is used for timing functions in USB isolators, then accurate detection of extended idle states and high-speed bus state transitions is achieved, but device complexity and cost increase
Solution Approach 1:
The patent replaces complex clock hardware and timing recovery circuits with a packet-based communication system that uses simple digital timing markers embedded within the data packets. This substitution eliminates the need for accurate external clock synchronization while maintaining the ability to detect bus state transitions and idle conditions through packet timing information.
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 solution enables high-speed USB communications across optical isolation barriers, reducing complexity and cost by eliminating the requirement for accurate clock signals and eUSB2 control messages, allowing for effective electrical isolation and full-speed data translation between USB2 devices.
Implementation Method 1
an optical transceiver, configured to convert the USB2 analog data signals to digital data for transmission across the isolation barrier to the other isolating eUSB2 repeater
Data Source
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Figure 3~4
AI summary
In described examples of a system and method for providing electrically isolated communications between two USB2 devices (305, 320), two isolating eUSB2 repeaters (345, 360) are used to implement a digital isolation barrier (330) between the two USB2 devices (305, 320). The isolating eUSB2 repeaters (345, 360) are configured to broker isolated communications between the two USB2 devices (305, 320) using a modified eUSB2 protocol that allows the two isolating eUSB2 repeaters (345, 360) to interoperate across the isolating barrier (330). The modified eUSB2 protocol allows the two isolating eUSB2 repeaters (345, 360) to broker isolating communications on behalf of the USB2 devices (305, 320) without the use of an accurate clock signal. The modified eUSB2 protocol used by the isolating eUSB2 repeaters (345, 360) is configured in particular to support certain end-of-packet translations between USB2 data and the modified eUSB2 protocol, management of certain USB2 bus state transitions, and assignment of roles to the two isolating eUSB2 repeaters (345, 360).