Multi-Stage Level Shifter for Transistor Overvoltage Protection

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Solution Overview

Problem

Electronic systems face challenges in efficiently converting low voltage signals to high voltage signals without overstressing individual transistors, particularly in circuits with varying voltage ranges.

Innovation Solution

A level shifter circuit comprising an input circuit with low voltage threshold switches, an output circuit with high voltage switches, and a buffer circuit, designed to generate and receive voltages within specific voltage ranges to ensure accurate signal translation while protecting transistors from overvoltage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a level shifter circuit converts low voltage signals to high voltage signals, then signal voltage range is expanded, but individual transistors may be overstressed

Engineering Contradiction:
Improvevoltage handling capabilityVSAvoidtransistor overvoltage stress
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The level shifter circuit is divided into multiple stages: a first circuit stage with low voltage threshold switches that receives the low voltage input signal, and a second circuit stage with high voltage threshold switches that generates the high voltage output signal. This segmentation allows each transistor to operate within its safe voltage range while achieving overall voltage conversion from low to high levels.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The first circuit stage acts as an intermediary between the low voltage input signal and the high voltage output signal. It converts the low voltage input into an intermediate signal that can then be safely amplified to high voltage by the second stage, preventing direct overvoltage stress on transistors.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If multiple circuit stages are used for voltage conversion, then transistor protection is improved, but circuit complexity increases

Engineering Contradiction:
Improvetransistor protection from overvoltageVSAvoidcircuit structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The circuit is segmented into two functional stages with distinct voltage handling roles. The first stage uses low voltage threshold switches optimized for low voltage operation, while the second stage uses high voltage threshold switches optimized for high voltage output. This clear segmentation provides protection while maintaining manageable complexity through functional specialization.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP4697599A1Level shifting circuit
Publication Date: 2026.02.18 STMICROELECTRONICS INT NV
  • EP4697599A1 patent drawingFigure 1~2
  • EP4697599A1 patent drawingFigure 3
  • EP4697599A1 patent drawingFigure 4

AI summary

A level shifter circuit is disclosed. The level shifter includes an input circuit including a plurality of low voltage threshold switches and configured to receive an input voltage and to generate a second voltage, where the second voltage varies between a first low voltage and a first high voltage; an output circuit including a first plurality of high voltage switches and configured to receive the second voltage and to generate a third voltage, where the third voltage varies between the first low voltage and a second high voltage; and a buffer circuit , the buffer circuit being configured to receive the third voltage and to generate a buffer circuit output voltage, where the buffer circuit output voltage varies between a second low voltage and the second high voltage.