Voltage Detector Power Clamp for Low-Leakage EOS Protection

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Solution Overview

Problem

Integrated circuits (ICs) are vulnerable to electrical over-stress (EOS) events, which can cause damage due to higher voltage levels, and existing protection methods, such as diode strings, allow significant leakage currents during normal operation, necessitating a more effective solution to protect ICs from EOS events.

Innovation Solution

A power clamp circuit is implemented, comprising a voltage detector and a clamp circuit that establish a local current path between power nodes in response to voltage differences exceeding a threshold, reducing the impact of EOS events on connected circuits by acting as a voltage clamp.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If diode strings are used to protect sensitive circuit elements during EOS events, then circuit reliability is improved, but significant leakage currents occur during normal circuit operation

Engineering Contradiction:

Improvecircuit reliabilityVSAvoidleakage currents

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The protection circuit transitions from a static diode string to a dynamic configuration using transistors that can switch between active and inactive states. The circuit responds to voltage conditions by activating protection only when EOS events are detected, rather than continuously conducting like diode strings, thereby eliminating normal operating leakage currents.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The circuit changes its electrical parameters dynamically based on operating conditions. During normal operation, the protection circuit presents high impedance to minimize leakage. During EOS events, it transitions to low impedance to provide protection, effectively changing its resistance parameter in response to voltage threshold detection.

Inventive Principle:

Principle #35Parameter changes

2Temperature

If polysilicon diodes are made large to avoid significant heat generation during EOS events, then thermal reliability is improved, but device area increases

Engineering Contradiction:

Improveheat generationVSAvoiddevice area

Core Design Contradiction:

TemperatureVSArea of stationary object

Solution Approach 1:

The invention extracts the protection function from large-area polysilicon diodes and implements it using smaller transistor-based circuitry. By separating the detection function (voltage threshold sensing) from the clamping function (current diversion), the design achieves EOS protection with significantly reduced device area compared to traditional diode implementations.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the physical diode structure with a transistor-based electronic switching system. This substitution allows the protection circuit to achieve the same thermal management goals through controlled switching and current routing rather than relying on the physical size and thermal mass of large polysilicon diodes.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS10284190B2Voltage detector circuits and methods

Publication Date: 2019.05.07 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A voltage detector includes a first node configured to have a first supply voltage, a second node configured to have a second supply voltage, and an output node. The voltage detector is configured to drive the output node to the first supply voltage in response to a difference between the first supply voltage and the second supply voltage exceeding a predetermined threshold voltage value.