USB Repeater Hysteresis Offset for High-Speed EOP Dribble
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Solution Overview
Problem
Conventional USB repeaters experience spurious signal transmission known as EOP dribble due to noise propagation during high-speed USB communications, which can lead to data corruption and link failures, and existing solutions require additional trim bits, increased power consumption, or die area without effectively addressing this issue independently of equalization settings.
Innovation Solution
The implementation of a USB repeater with a hysteresis stage that opposes the differential signal generated at its output nodes, reducing noise transmission without requiring additional trim bits or increasing power consumption, and this reduction is achieved independently of equalization settings, thereby minimizing EOP dribble in high-speed USB communications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional USB repeaters transmit differential signals during high-speed USB communications, then data transmission is enabled, but noise propagation causes EOP dribble leading to data corruption
Solution Approach 1:
The hysteresis stage applies preliminary anti-action by generating an offset voltage that opposes the differential signal during the end-of-packet period. This offset voltage counteracts noise before it can propagate through the repeater, preventing EOP dribble from occurring in the first place rather than attempting to correct it after transmission.
Solution Approach 2:
The invention converts the harmful noise signal into a beneficial effect by using the hysteresis stage to detect the presence of noise and generate an opposing offset voltage. The same signal path that carries the noise also carries the corrective offset, transforming the noise problem into a self-correcting mechanism that eliminates EOP dribble.
2Object-generated harmful factors
If additional trim bits are added to reduce EOP dribble, then noise transmission is attenuated, but die area and manufacturing complexity increase
Solution Approach 1:
The hysteresis stage operates autonomously without requiring external trim bits or calibration. It automatically generates the appropriate offset voltage based on the differential signal it receives, making the noise attenuation function self-regulating and eliminating the need for additional control bits that would increase device complexity.
3Object-generated harmful factors
If hysteresis offset is applied to reduce EOP dribble, then noise propagation is reduced, but signal jitter and latency may increase
Solution Approach 1:
The hysteresis offset is dynamically adjusted based on the differential signal conditions rather than being a fixed value. The offset magnitude changes with the signal state, providing strong noise suppression when needed while minimizing impact on normal signal transmission, thus reducing both jitter and latency compared to static hysteresis approaches.
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 approach effectively reduces EOP dribble in USB communications without adding significant jitter, latency, or increasing die area or power consumption, ensuring reliable data transmission by attenuating noise at the repeater output.
Implementation Method 1
An offset is applied to a hysteresis stage in the receiver that is coupled to the first and second output nodes
Data Source
AI summary
Universal Serial Bus (USB) repeater circuits and methods of operating the same for communicating data signals from a first pair of data terminals to a second pair of data terminals of the repeater. In a first channel, an amplifier stage in a receiver amplifies a differential signal received at the first pair of data terminals to generate a differential signal at first and second output nodes of the receiver, and a transmitting circuit transmits a differential signal at the second pair of data terminals responsive to the differential signal at the first and second output nodes of the receiver. The receiver includes a hysteresis stage that receives an offset in opposition to the differential signal at the first and second output nodes of the receiver. End-of-packet (EOP) dribble in USB communications in the HS mode is reduced by the offset at the hysteresis stage.