Open-Drain Repeater Using Current Detection for Fast I2C Signals

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Solution Overview

Problem

Conventional repeaters in open-drain systems face challenges such as static offset issues, high costs due to large pull-up resistors, and inability to handle high-speed communications, while also struggling with signal integrity and rise-time.

Innovation Solution

A repeater apparatus comprising a first port, a second port, a current detector, a transistor, and a control logic circuit, where the current detector and control logic circuit work together to eliminate the need for external pull-up resistors, reduce static voltage offset, and support high-frequency communications by determining current flow to control the transistor's operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If pull-up resistors are used to detect transmission and reception of data, then data detection capability is improved, but device size and cost increase

Engineering Contradiction:

Improvedata detection capabilityVSAvoiddevice size

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

The patent replaces the mechanical/electrical pull-up resistor system with a field-based detection system using a current detector that senses current flow direction through the transistor. This substitution eliminates the need for large physical resistors while maintaining data detection capability, directly resolving the contradiction between measurement precision and device size.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If static offset buffers are used in repeaters, then signal buffering capability is improved, but output low level detection accuracy deteriorates

Engineering Contradiction:

Improvesignal buffering capabilityVSAvoidoutput low level detection accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent extracts and removes the static offset buffer component from the repeater system. By eliminating this component, the harmful static offset effect is removed, allowing accurate detection of output low levels while maintaining signal buffering capability through the current detector and transistor combination.

Inventive Principle:

Principle #2Taking out (Extraction)

3Productivity

If conventional repeater circuitry is used, then basic signal repetition is achieved, but high-speed communication handling capability deteriorates

Engineering Contradiction:

Improvebasic signal repetitionVSAvoidcommunication speed

Core Design Contradiction:

ProductivityVSSpeed

Solution Approach 1:

The patent introduces dynamic control through the control logic circuit that responds to real-time current detector signals. This dynamic system can adapt to high-speed communication requirements by quickly detecting and responding to signal changes, unlike static conventional repeater circuitry, thereby enabling high-speed communication handling while maintaining basic signal repetition function.

Inventive Principle:

Principle #15Dynamics

4Adaptability or versatility

If complicated power hungry circuitry is used, then repeater functionality is improved, but energy consumption increases

Engineering Contradiction:

Improverepeater functionalityVSAvoidenergy consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent implements a self-service mechanism where the current detector uses the existing signal current flow to detect transmission and reception states without requiring additional power-hungry circuitry. The system serves itself by utilizing the natural current flow in the open-drain configuration, reducing energy consumption while maintaining full repeater functionality.

Inventive Principle:

Principle #25Self-service

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 results in a smaller, cost-effective repeater with improved performance, supporting high-frequency communications like I2C standard speed, fast mode, and fast-mode plus, while maintaining signal integrity and reducing rise-time.

Implementation Method 1

A current detector input of the current detector is coupled to the first port

Methodology Applied

Scientific EffectElectrical current detection: Conduction (electrical)

Implementation Method 2

A transistor channel electrode of the transistor is coupled to the second port. A control logic circuit input of the control logic circuit is coupled to the current detector output, and a control logic circuit output of the control logic circuit is coupled to a transistor control electrode of the transistor

Methodology Applied

Scientific EffectTransistor operation: Conduction (electrical)

Data Source

PatentUS11133802B2Repeater for an open-drain communication system using a current detector and a control logic circuit

Publication Date: 2021.09.28 TEXAS INSTRUMENTS INC

AI summary

This disclosure generally relates to repeaters, and, in particular, repeaters for open-drain systems. In one embodiment, an apparatus comprises a first port, a second port, a current detector, a transistor, and a control logic circuit. A current detector input of the current detector is coupled to the first port. A transistor channel electrode of the transistor is coupled to the second port. A control logic circuit input of the control logic circuit is coupled to the current detector output, and a control logic circuit output of the control logic circuit is coupled to a transistor control electrode of the transistor.