USB Repeater Circuit for Accurate Remote Wake Resume Detection
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Solution Overview
Problem
Conventional USB repeaters face challenges in accurately detecting the end of host signaling during Remote Wake transitions due to tight timing constraints without a highly accurate clock, leading to potential misalignment in peripheral device states.
Innovation Solution
Implementing a detection circuit with current sources and comparators to detect voltage changes on signal lines, and using switch-actuated pull-up resistors to manage signal states, enabling seamless data flow direction changes during Remote Wake signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a timer is used to manage Remote Wake signaling without a highly accurate clock, then the device complexity is reduced, but the measurement precision of timing constraints deteriorates
Solution Approach 1:
The patent introduces a detection circuit as an intermediary component that mediates between the timer and the signaling process. This circuit actively monitors the differential signal lines and generates detection signals when specific voltage thresholds are crossed, thereby compensating for the lack of high-precision clock timing while maintaining accurate detection of host signaling events.
Solution Approach 2:
The detection circuit implements a feedback mechanism by continuously monitoring the signal lines and providing real-time detection signals to the control logic. This feedback allows the system to adapt to actual signaling conditions and make precise state transitions without relying on predetermined timer values, thus achieving accurate timing measurement without requiring a highly accurate clock.
2Reliability
If the peripheral remains in the K state for a longer duration to ensure host response, then the reliability of Remote Wake is improved, but the risk of missing the end of host signaling increases
Solution Approach 1:
The detection circuit provides continuous feedback monitoring of the differential signal lines during the Remote Wake sequence. By actively detecting voltage level changes and generating detection signals, the system can precisely identify the end of host signaling regardless of how long the peripheral maintains the K state, thus preventing information loss while ensuring reliable host response.
Solution Approach 2:
The patent replaces the mechanical timing approach (using a highly accurate clock and predetermined timer values) with an electronic detection system that actively monitors signal voltage levels. This substitution allows the system to determine the end of host signaling based on actual electrical signal conditions rather than time-based assumptions, eliminating the trade-off between holding duration and detection accuracy.
3Measurement precision
If a highly accurate clock is used to ensure precise timing detection, then the measurement precision of timing constraints is improved, but the device complexity and cost increase
Solution Approach 1:
The detection circuit serves as an intermediary that bridges the gap between the simple timer and the requirement for precise timing measurement. By introducing this intermediate component that actively monitors signal lines and generates detection signals based on voltage thresholds, the system achieves high measurement precision without needing a complex high-accuracy clock system.
Solution Approach 2:
The patent substitutes the mechanical/time-based measurement system (highly accurate clock) with an electrical field-based detection system. The detection circuit monitors voltage levels on the differential signal lines and generates detection signals when specific threshold conditions are met, thereby achieving precise timing measurement through electrical signal monitoring rather than time-based counting.
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
Enables precise timing in USB repeaters to ensure accurate detection of host signaling, reducing the risk of missed signals and improving the efficiency of transitioning between sleep and resume states without requiring a highly accurate clock.
Implementation Method 1
detecting a changed signal level on the second signal line using the detection circuit
Implementation Method 2
enabling a detection circuit of the first-device-side transceiver including applying current to the second signal line; detecting a changed signal level on the second signal line using the detection circuit
Implementation Method 3
disabling a resistive element coupled between a power supply voltage and a second signal line of the pair of signal lines
Data Source
AI summary
Various configurations of high-speed data communication devices, e.g., repeaters, interfacing between a host and a peripheral, and methods of operating the same, are provided to improve the Remote Wake sequence. Repeaters include circuitry to detect the start of Resume signaling or the end of Resume, following initiation of Remote Wake. In an example, pull-up resistors coupled to upstream differential signal lines and a detection circuit with a current source are controlled to detect the start of Resume signaling. In another example, the upstream-side pull-resistors and an enable signal to an upstream-side transmitter are controlled to detect the end of Resume.