ESD Protection Circuit Using Diode String and Transistor Stack

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Solution Overview

Problem

Electro-static discharge (ESD) events can damage integrated circuits by transferring energy, rendering them less operable or inoperable, and existing protection circuits may not effectively manage mixed voltage conditions within the circuits.

Innovation Solution

An ESD protection circuit comprising an ESD detection circuit and an ESD clamp circuit, utilizing a string of diodes and transistors, including n-channel and p-channel MOSFETs, connected between a voltage source and ground, which activates or deactivates the clamp circuit based on voltage and current conditions to prevent damage from ESD events.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an ESD protection circuit is added to protect integrated circuits from ESD events, then the reliability of the circuit is improved, but the device complexity increases

Engineering Contradiction:

Improveprotection against ESD eventsVSAvoidcircuit structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The ESD protection circuit is pre-configured with detection circuits and clamp circuits that are activated before ESD damage occurs. The detection circuit monitors voltage conditions and preliminarily prepares the clamp circuit to shunt ESD current away from sensitive IC components, preventing damage before it happens.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The ESD protection circuit acts as an intermediary between the external environment and the sensitive IC components. It includes intermediate elements such as detection circuits, clamp circuits, and current paths that intercept and redirect ESD energy before it reaches the IC, serving as a protective buffer zone.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the ESD protection circuit activates the clamp circuit to shunt ESD current, then the protection effectiveness is improved, but the loss of energy increases

Engineering Contradiction:

ImproveESD protection effectivenessVSAvoidenergy dissipation

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The ESD protection circuit converts the harmful ESD energy into a beneficial protective action. The clamp circuit intentionally provides a controlled path for ESD current to flow through safe components, transforming the destructive ESD event into a manageable current flow that protects the IC while dissipating energy through designated protective elements.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The ESD protection circuit extracts the harmful ESD current from the main circuit path and redirects it through a separate clamp circuit path. By separating the ESD current path from the IC power and signal paths, the circuit removes the harmful energy from the sensitive components while allowing controlled energy dissipation in the protective clamp circuit.

Inventive Principle:

Principle #2Taking out (Extraction)

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 ESD protection circuit effectively inhibits damage from ESD events by controlling the flow of current and maintaining voltages within safe limits for integrated circuit components, ensuring reliable operation during both normal and ESD conditions.

Implementation Method 1

a string of diodes connected between a first voltage source and a second voltage source, wherein the string of diodes is configured to provide a specified voltage at a first node

Methodology Applied

Scientific EffectDiode voltage drop: Diode

Implementation Method 2

an ESD detection circuit comprising a string of diodes connected between a first voltage source and a second voltage source

Methodology Applied

Scientific EffectElectrical field detection: Electric Field

Implementation Method 3

an ESD clamp circuit comprising a stack of transistors connected between the first voltage source and the second voltage source, wherein a gate of the first stack transistor is connected to a drain of a first transistor of the ESD detection circuit

Methodology Applied

Scientific EffectMOSFET current conduction: Conduction (electrical)

Data Source

PatentUS9941267B2Electro-static discharge protection circuit

Publication Date: 2018.04.10 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

An electro-static discharge (ESD) protection circuit is configured to protect circuitry during an ESD event. The ESD protection circuit includes an ESD detection circuit and an ESD clamp circuit. The ESD clamp circuit includes a stack of transistors that is controlled by the ESD detection circuit. A first stack transistor of the stack of transistors includes a deep n-well. The stack of transistors is configured to be activated responsive to detecting the ESD event. The stack of transistors is configured to be deactivated responsive to detecting at least one of normal current conditions or normal voltage conditions. The ESD detection circuit includes a string of diodes. The string of diodes is configured to be activated responsive to detecting the ESD event. The stack of transistors is configured to be a voltage divider responsive to normal voltage conditions.