Wired Transmitter Voltage-Domain Isolation for Overvoltage Protection

Solution Overview

Problem

Transistors with lower withstand voltage are vulnerable to damage from high-voltage signals in Ethernet applications, leading to reduced reliability of signal transmitters.

Innovation Solution

Implementing a wired transmitter with a digital-to-analog converter (DAC) and line driver circuits that operate in different voltage domains, using transistors with lower withstand voltage, and incorporating overvoltage protection mechanisms to safeguard these circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If transistors with lower withstand voltage are used to implement the transmitter, then manufacturing cost and device complexity are reduced, but the transistors become vulnerable to damage from high-voltage signals

Engineering Contradiction:

Improvetransistor manufacturingVSAvoidtransistor durability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The transmitter is divided into multiple voltage domains: a first voltage domain (1.8V) for the DAC and a second voltage domain (3.3V) for the line driver. This segmentation allows low-withstand-voltage transistors to be used in the DAC while protecting them from high-voltage signals through domain isolation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A voltage domain isolation mechanism acts as an intermediary between the DAC and line driver. The isolation circuit prevents high-voltage signals from the line driver from directly affecting the low-voltage DAC transistors, thereby protecting them without requiring high-withstand-voltage transistors throughout the entire system.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Use of energy by moving object

If transistors with lower withstand voltage are used, then power consumption is reduced, but the transmitter reliability deteriorates due to vulnerability to overvoltage

Engineering Contradiction:

Improvepower consumptionVSAvoidtransmitter reliability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The transmitter is divided into multiple voltage domains: a first voltage domain (1.8V) for the DAC and a second voltage domain (3.3V) for the line driver. This segmentation allows low-withstand-voltage transistors to be used in the DAC while protecting them from high-voltage signals through domain isolation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A voltage domain isolation mechanism acts as an intermediary between the DAC and line driver. The isolation circuit prevents high-voltage signals from the line driver from directly affecting the low-voltage DAC transistors, thereby protecting them without requiring high-withstand-voltage transistors throughout the entire system.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If voltage domain isolation is implemented, then overvoltage protection is achieved, but device complexity increases

Engineering Contradiction:

Improveovervoltage protectionVSAvoidcircuit structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The transmitter is divided into multiple voltage domains: a first voltage domain (1.8V) for the DAC and a second voltage domain (3.3V) for the line driver. This segmentation allows low-withstand-voltage transistors to be used in the DAC while protecting them from high-voltage signals through domain isolation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A voltage domain isolation mechanism acts as an intermediary between the DAC and line driver. The isolation circuit prevents high-voltage signals from the line driver from directly affecting the low-voltage DAC transistors, thereby protecting them without requiring high-withstand-voltage transistors throughout the entire system.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS12445154B2Wired transmitter with overvoltage protection

Publication Date: 2025.10.14 SIGMASTAR TECH LTD

AI summary

A wired transmitter includes a digital-to-analog converter (DAC) and a line driver. The DAC generates first output signals according to a digital code, wherein a first circuit in the DAC operates in a first voltage domain and a second circuit of the DAC operates in a second voltage domain, and an upper limit of the first voltage domain is lower than an upper limit of the second voltage domain. The line driver operates in the second voltage domain, and generates second output signals according to the first output signals. Each of the DAC and the line driver is implemented by transistors corresponding to the first voltage domain.