USB Repeater Hysteresis Offset for End-of-Packet Dribble

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Solution Overview

Problem

Conventional USB repeaters experience spurious signal levels known as EOP dribble due to noise transmission after an end-of-packet sequence, which can lead to data corruption and link failure, especially in high-speed USB communications.

Innovation Solution

A USB repeater design that incorporates a hysteresis stage with an offset applied to the differential signal, opposing the signal developed by the amplifier stage, reduces EOP dribble without increasing die area, power consumption, or requiring additional trim bits, and operates independently of receiver equalization settings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional USB repeater design is used, then the repeater can transmit high-speed USB signals, but spurious signal levels (EOP dribble) occur due to noise transmission after end-of-packet sequences

Engineering Contradiction:

Improvesignal integrityVSAvoidEOP dribble

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies preliminary anti-action by introducing a hysteresis stage that generates an offset signal in opposition to the differential signal before noise can cause harmful EOP dribble. This preemptive counter-action prevents the spurious signal levels from occurring in the first place, rather than attempting to filter or correct them afterward.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The hysteresis stage acts as an intermediary between the amplifier stage and the output, mediating the differential signal by adding an offset that counteracts noise. This intermediate processing stage prevents noise from propagating through the repeater and causing EOP dribble, while allowing valid signals to pass through unchanged.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If additional circuitry is added to reduce EOP dribble, then signal integrity improves, but die area and power consumption increase

Engineering Contradiction:

Improvesignal integrityVSAvoiddie area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent merges the hysteresis stage with the existing amplifier stage, combining multiple functions into a single integrated circuit block. By integrating the offset-generating hysteresis circuitry within the amplifier stage rather than adding it as a separate component, the solution reduces the overall die area while maintaining the ability to suppress EOP dribble.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If additional circuitry is added to reduce EOP dribble, then signal integrity improves, but power consumption increases

Engineering Contradiction:

Improvesignal integrityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

4Reliability

If hysteresis offset is applied to counteract noise, then EOP dribble is reduced, but signal distortion may occur

Engineering Contradiction:

Improvenoise suppressionVSAvoidsignal fidelity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies dynamics by making the hysteresis offset adaptive rather than fixed. The offset signal dynamically adjusts based on the differential signal conditions, being applied only when needed to counteract noise and EOP dribble. This dynamic behavior ensures that valid signals are not distorted while noise is suppressed, maintaining signal fidelity.

Inventive Principle:

Principle #15Dynamics

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 effectively reduces or eliminates EOP dribble in high-speed USB communications, preventing data errors and link failures while maintaining signal integrity without adding jitter or latency.

Implementation Method 1

A hysteresis stage with an offset applied to the differential signal, opposing the signal developed by the amplifier stage

Methodology Applied

Scientific EffectHysteresis: Hysteresis

Data Source

PatentUS11984941B2Rejection of end-of-packet dribble in high speed universal serial bus repeaters

Publication Date: 2024.05.14 TEXAS INSTRUMENTS INC

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.