I2C Transmitter and Receiver Stable Reference Voltage

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Solution Overview

Problem

In battery-operated circuits, the varying supply voltage affects the drive capability of NMOS transistors in I2C transmitters and receivers, making it difficult to meet stringent specifications like speed and current consumption, especially at higher data signaling rates, leading to reduced efficiency and battery life.

Innovation Solution

Implementing a stable reference voltage in the last stage of the I2C transmitter and the first stage of the receiver, instead of a variable supply voltage, to reduce drive spread and prevent short circuit current consumption, allowing operation at faster speeds and extended battery life.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a variable supply voltage is used for all stages of the transmitter and receiver, then the circuit can operate across a wide voltage range, but the drive capability varies significantly and short circuit current is consumed

Engineering Contradiction:

Improvevoltage rangeVSAvoidshort circuit current

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The transmitter and receiver circuits are segmented into multiple stages, with only the critical stages (last stage of transmitter pre-driver and first stage of receiver) supplied with stable reference voltage, while other stages continue to use variable supply voltage. This selective segmentation reduces overall power consumption without sacrificing adaptability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Stable reference voltage is applied locally to specific critical stages where it is most needed (transmitter pre-driver output stage and receiver input stage), rather than uniformly to all stages. This local quality approach minimizes energy loss in the most sensitive areas while maintaining voltage adaptability elsewhere.

Inventive Principle:

Principle #3Local quality

2Adaptability or versatility

If a variable supply voltage is used for the transmitter, then the circuit adapts to battery voltage changes, but the transmitter drive spread increases and operating speed decreases

Engineering Contradiction:

Improvebattery voltage adaptationVSAvoidtransmitter operating speed

Core Design Contradiction:

Adaptability or versatilityVSSpeed

Solution Approach 1:

The transmitter is divided into stages with different voltage supply strategies. The pre-driver and driver stages use variable supply voltage for battery adaptation, while the critical last stage of the pre-driver uses stable reference voltage to maintain drive capability and operating speed.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Stable reference voltage is applied locally to the last stage of the pre-driver where drive capability is most critical, while other transmitter stages use variable supply voltage. This localized approach maintains high operating speed without requiring stable voltage throughout the entire transmitter.

Inventive Principle:

Principle #3Local quality

3Speed

If a stable reference voltage is used in the last stage of the transmitter pre-driver, then the transmitter drive spread decreases and operating speed increases, but the circuit complexity increases

Engineering Contradiction:

Improvetransmitter operating speedVSAvoidvoltage supply structure

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The voltage supply system is segmented into stable reference voltage path and variable supply voltage path, with the stable path used only for the critical last stage of the pre-driver. This minimal segmentation achieves speed improvement without substantially increasing overall circuit complexity.

Inventive Principle:

Principle #1Segmentation

4Loss of energy

If a stable reference voltage is used in the first stage of the receiver, then short circuit current is prevented, but the receiver cannot fully utilize variable supply voltage benefits

Engineering Contradiction:

Improveshort circuit current preventionVSAvoidsupply voltage flexibility

Core Design Contradiction:

Loss of energyVSAdaptability or versatility

Solution Approach 1:

The receiver is segmented such that only the first stage uses stable reference voltage to prevent short circuit current, while subsequent stages continue to use variable supply voltage for full adaptability benefits. This selective segmentation resolves the contradiction between energy loss prevention and voltage flexibility.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Stable reference voltage is applied locally to the first stage of the receiver where short circuit current occurs, while the rest of the receiver uses variable supply voltage. This localized application prevents energy loss without sacrificing overall supply voltage flexibility.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS10848147B2High performance I2C transmitter and bus supply independent receiver, supporting large supply voltage variations

Publication Date: 2020.11.24 STMICROELECTRONICS INT NV

AI summary

One or more embodiments are directed to inter-integrated circuit (I2C) transmitters, receivers, and devices that utilize a stable reference voltage for driving a pre-driver of the transmitter and for driving a first input stage of the receiver. One embodiment is directed to a device A device that includes an inter-integrated circuit (I2C) transmitter and an I2C receiver. The I2C transmitter includes a driver coupled to an I2C data line, and a pre-driver coupled to a variable first supply voltage, a second supply voltage, and a reference voltage. The pre-driver is configured to output a control signal to a control terminal of the driver. The I2C receiver includes a first stage coupled to the I2C data line, the variable first supply voltage, the second supply voltage, and the reference voltage.