Reverse-Direction HEMT Input Protection Circuit

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Solution Overview

Problem

Conventional MOSFETs face challenges in controlling current flow when negatively biased due to the presence of a body diode, which affects their reverse conduction characteristics, whereas high-electron-mobility transistors (HEMTs) lack p-n junctions, resulting in different voltage characteristics and the need for innovative solutions to manage reverse conduction and electrostatic discharge protection.

Innovation Solution

The use of reverse-direction HEMTs (RDHEMTs) with specific circuit configurations, such as the input protection and level shifter circuits, that exploit their unique reverse conduction characteristics to provide voltage clamping and electrostatic discharge protection by leveraging the reverse conduction onset voltage, allowing for effective management of voltage excursions and overvoltage events.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional MOSFETs are used for input protection, then electrostatic discharge protection can be provided, but reverse conduction characteristics are affected by the body diode

Engineering Contradiction:

Improveelectrostatic discharge protectionVSAvoidreverse conduction characteristics

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent extracts and removes the body diode from the MOSFET structure by using a triple-well CMOS process to create an isolated well that eliminates the parasitic p-n junction. This allows the MOSFET to function without the harmful reverse conduction path while maintaining forward conduction capability for ESD protection.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies local quality by creating a specialized isolated well region within the MOSFET structure that has different electrical properties from the bulk substrate. This localized modification changes the reverse conduction characteristics in the critical region while leaving the rest of the device structure intact.

Inventive Principle:

Principle #3Local quality

2Object-generated harmful factors

If HEMTs are used to eliminate body diode effects, then reverse conduction characteristics improve, but p-n junctions are absent resulting in different voltage characteristics

Engineering Contradiction:

Improvereverse conduction characteristicsVSAvoidvoltage characteristics

Core Design Contradiction:

Object-generated harmful factorsVSAdaptability or versatility

Solution Approach 1:

The patent merges the advantages of HEMTs (no body diode) with the versatility of MOSFETs by integrating the HEMT channel structure into a CMOS-compatible process. This combination provides both improved reverse conduction characteristics and the ability to maintain standard voltage levels through gate control.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent changes the fundamental parameter of the transistor channel from silicon-based MOSFET to III-V族 HEMT material, which fundamentally alters the voltage characteristics and eliminates the body diode effect while enabling new operating modes including reverse conduction control.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If reverse-direction HEMTs are used for voltage clamping, then electrostatic discharge protection is provided, but circuit configuration complexity increases

Engineering Contradiction:

Improveelectrostatic discharge protectionVSAvoidcircuit configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent makes the HEMT device universal by enabling it to perform multiple functions: forward conduction for normal operation, reverse conduction for voltage clamping, and ESD protection. This multi-functionality eliminates the need for separate protection circuits, reducing overall system complexity despite the advanced device structure.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

RDHEMTs effectively clamp voltages and provide electrostatic discharge protection by conducting current at the reverse conduction onset voltage, ensuring that integrated circuit input pads do not exceed certain voltage thresholds, thereby safeguarding against excessive positive or negative voltages.

Implementation Method 1

RDHEMTs effectively clamp voltages and provide electrostatic discharge protection by conducting current at the reverse conduction onset voltage

Methodology Applied

Scientific EffectReverse conduction:

Implementation Method 2

provide electrostatic discharge protection by conducting current at the reverse conduction onset voltage

Methodology Applied

Scientific EffectElectrostatic discharge: Electrostatic Discharge

Data Source

PatentUS11456597B2Input protection and level shifter circuit

Publication Date: 2022.09.27 WHITNEY DAVID L

AI summary

Voltage clamping and level shifting is provided. A first reverse direction high-electron-mobility transistor includes a source connected to an input pad, and a drain connected to a first reference voltage. A second reverse direction high-electron-mobility transistor includes a source and a gate connected to a second reference voltage, and a drain connected to the input pad. A gate of the first reverse direction high-electron-mobility transistor is connected to the second reference voltage. Level shifting is provided by an arrangement of three high-electron-mobility transistor and a resistive element