Stacked Thyristor Protection Circuit for High Voltage Tolerance

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Solution Overview

Problem

Electronic systems face damage from electrical overstress events, such as EOS and ESD, which can cause overvoltage conditions and high power dissipation, leading to issues like gate oxide punch-through and junction damage, especially in high data rate applications like HDMI 2.1, where existing protection circuitry may not be sufficient to handle high voltage tolerant conditions without impacting performance.

Innovation Solution

A semiconductor die with a stacked thyristor protection device, comprising a thyristor and a resistive thyristor connected in a stack between signal and ground pads, enhancing holding voltage while maintaining low trigger voltage, utilizing cross-coupled PNP and NPN bipolar transistors to provide both thyristor and resistor characteristics based on current flow, thus offering high voltage tolerance and current handling capability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional thyristor protection device is used, then the circuit can handle electrical overstress events, but the holding voltage is insufficient for high voltage tolerant applications

Engineering Contradiction:

Improveholding voltageVSAvoidvoltage tolerance range

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The protection device is segmented into two distinct thyristors with different holding voltage characteristics. The first thyristor has a lower holding voltage for normal operation, while the second thyristor has a higher holding voltage for high voltage tolerant conditions. This segmentation allows the circuit to handle both low voltage precision operations and high voltage stress events effectively.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs a composite protection structure combining two thyristor devices with complementary characteristics. The first thyristor (e.g., 330V holding voltage) and second thyristor (e.g., 660V holding voltage) work together in parallel, creating a composite protection system that provides both low-voltage precision and high-voltage tolerance, effectively extending the voltage protection range.

Inventive Principle:

Principle #40Composite materials

2Reliability

If the holding voltage is increased to handle high voltage conditions, then voltage tolerance improves, but the trigger voltage may be adversely impacted

Engineering Contradiction:

Improvevoltage toleranceVSAvoidtrigger voltage

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The protection function is segmented between two independent thyristors, each with optimized trigger and holding characteristics. The first thyristor triggers at lower voltage for normal operation, while the second thyristor triggers at higher voltage for overvoltage conditions. This segmentation ensures that high holding voltage does not adversely impact low-voltage trigger sensitivity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The protection system dynamically adapts its characteristics based on operating conditions. Under normal voltage conditions, the first thyristor provides precise protection with low trigger voltage. When voltage exceeds certain thresholds, the second thyristor becomes active, providing high voltage tolerance. This dynamic behavior allows the system to optimize both trigger sensitivity and voltage tolerance across different operating ranges.

Inventive Principle:

Principle #15Dynamics

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 stacked thyristor protection device effectively handles high operating voltages and fast-transient current densities with reduced parasitic capacitance, ensuring reliability in high data rate interfaces by providing enhanced holding voltage and current handling without degrading trigger voltage performance, suitable for applications like HDMI 2.1 and other high-speed communication interfaces.

Implementation Method 1

a stacked thyristor protection device, comprising a thyristor and a resistive thyristor connected in a stack between signal and ground pads

Methodology Applied

Scientific EffectThyristor effect:

Implementation Method 2

The resistive thyristor includes a PNP bipolar transistor and an NPN bipolar transistor that are cross-coupled, and an electrical connection between a collector of the PNP bipolar transistor and a collector of the NPN bipolar transistor

Methodology Applied

Scientific EffectBipolar transistor effect:

Data Source

PatentUS11342323B2High voltage tolerant circuit architecture for applications subject to electrical overstress fault conditions

Publication Date: 2022.05.24 ANALOG DEVICES INC

AI summary

A semiconductor die with high-voltage tolerant electrical overstress circuit architecture is disclosed. One embodiment of the semiconductor die includes a signal pad, a ground pad, a core circuit electrically connected to the signal pad, and a stacked thyristor protection device. The stacked thyristor includes a first thyristor and a resistive thyristor electrically connected in a stack between the signal pad and the ground pad, which enhances the holding voltage of the circuit relatively to an implementation with only the thyristor. Further, the resistive thyristor includes a PNP bipolar transistor and a NPN bipolar transistor that are cross-coupled, and an electrical connection between a collector of the PNP bipolar transistor and a collector of the NPN bipolar transistor. This allows the resistive thyristor to exhibit both thyristor characteristics and resistive characteristics based on a level of current flow.