GaN ESD Protection Circuit for Gate Voltage Overshoot Clamping

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Solution Overview

Problem

GaN devices are susceptible to damage from electrostatic discharge (ESD) due to their smaller gate-to-source breakdown voltage, which can induce high-intense electric fields and current, particularly in power GaN devices.

Innovation Solution

An ESD protection circuit using GaN-based devices, including resistors, capacitors, and high electron mobility transistors (HEMTs), integrated on a GaN substrate, with a structure that includes power HEMT, 2 DEG resistors, and LV-HEMTs to provide protection against voltage overshoot.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If GaN devices are used to achieve high power and high frequency performance, then power consumption is reduced and efficiency is improved, but the gate-to-source breakdown voltage becomes smaller making the device susceptible to ESD damage

Engineering Contradiction:

Improvepower consumptionVSAvoidgate-to-source breakdown voltage

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

A protection circuit is introduced as an intermediary between the ESD source and the GaN device gate. This circuit includes a first protection path with a first trigger device and first clamp device, and a second protection path with a second trigger device and second clamp device, which activate under different voltage conditions to clamp and dissipate ESD energy before it reaches the vulnerable gate terminal.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The protection circuit is segmented into multiple independent protection paths (first and second protection paths) that operate in parallel. Each path has its own trigger and clamp devices configured to respond to different voltage thresholds, allowing selective activation based on the severity of the ESD event while maintaining protection across a wide voltage range.

Inventive Principle:

Principle #1Segmentation

2Speed

If the gate-to-source breakdown voltage is kept small to enable high frequency operation, then switching frequency is improved, but the device becomes more vulnerable to voltage overshoot and ESD

Engineering Contradiction:

Improveswitching frequencyVSAvoidvoltage overshoot susceptibility

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The protection circuit is designed to activate before ESD damage can occur to the GaN device. The trigger devices are configured with threshold voltages that cause them to activate in advance of the damage threshold, preemptively clamping the voltage and redirecting ESD current through safe paths before the vulnerable gate terminal is exposed to damaging voltage levels.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The protection circuit converts the harmful ESD energy into a beneficial protective action by redirecting the high-intensity ESD current through dedicated clamping paths rather than allowing it to damage the gate. The ESD energy is dissipated through controlled conduction in the protection circuit components, transforming a destructive force into a protected state for the GaN device.

Inventive Principle:

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

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 circuit effectively protects GaN devices from ESD by establishing controlled conduction paths to dissipate surge voltages, reducing the risk of gate damage and enhancing the reliability of GaN-based circuits.

Implementation Method 1

a first 2 DEG resistor with one terminal coupled to the gate, a first trigger with one terminal coupled to another terminal of the first 2 DEG resistor

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

Electrostatic discharge (ESD) is one type of voltage overshoot, resulting from sudden release of electrostatic charges, inducing high intense electric field and current in ICs

Methodology Applied

Scientific EffectElectrostatic discharge: Electrostatic Discharge

Data Source

PatentUS20250311441A1Electrostatic discharge protection circuit using gan-based devices

Publication Date: 2025.10.02 UNITED MICROELECTRONICS CORP

AI summary

An ESD protection circuit using GaN devices, with a ESD block including a first 2 DEG resistor with one terminal coupled to a gate of a power HEMT, a first trigger with one terminal coupled to another terminal of the first 2 DEG resistor and with another terminal coupled to a reference voltage, a first LV-HEMT with a first gate coupled to the another terminal of the first 2 DEG resistor and a first drain couple to the gate, a second trigger with one terminal coupled to the gate, a second 2 DEG resistor with one terminal coupled to another terminal of the second trigger and another terminal coupled to the reference voltage, and a second LV-HEMT with a second gate coupled to the another terminal of the second trigger and a second drain coupled to the first source and a second source coupled to the reference voltage.