GaN Switching Device Emulated Diode Monolithic Integration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
III-nitride transistors, such as GaN HEMTs, lack an intrinsic diode, necessitating a separate diode for over-voltage protection, which is difficult and complex to integrate, limiting their adoption in high-performance switching applications.
Innovation Solution
A III-nitride switching device with an emulated diode is achieved by using dual threshold transistors, where a low threshold GaN diode connected transistor provides Schottky-like diode performance by shorting the gate to the source with low resistance, and a high threshold GaN transistor handles switching, enabling monolithic integration and efficient over-voltage protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate diode is integrated into a GaN HEMT process to provide over-voltage protection, then the device functionality is improved, but the manufacturing complexity increases significantly
Solution Approach 1:
The patent merges the diode functionality into the GaN HEMT structure by utilizing the existing source-drain path and gate control mechanism. The diode is formed by configuring the transistor with the gate shorted to the source, creating a diode-connected transistor that provides reverse polarity protection without requiring a separate diode structure, thus simplifying monolithic integration.
Solution Approach 2:
The GaN HEMT transistor structure is designed to serve dual functions: as a switching transistor during normal operation and as a protective diode during reverse voltage conditions. This multi-functionality eliminates the need for separate dedicated diode structures, reducing manufacturing complexity while maintaining reliability.
2Loss of energy
If Schottky-like diode performance with low forward voltage drop is implemented, then the switching efficiency is improved, but the integration complexity into a single device increases
Solution Approach 1:
The patent achieves low forward voltage drop by carefully controlling the threshold voltage parameter of the GaN HEMT. By selecting transistors with appropriately low threshold voltages and optimizing the gate-source voltage during diode operation, the forward voltage drop is minimized to approach Schottky-like performance, while maintaining integration within the standard GaN HEMT process.
3Reliability
If a separate diode is used for over-voltage protection in III-nitride transistors, then the protection functionality is achieved, but the circuit design complexity and component count increase
Solution Approach 1:
The protective diode function is merged with the main switching transistor by using the same physical structure in a diode-connected configuration. This integration reduces the component count from two separate devices (transistor plus diode) to a single multi-functional device, simplifying circuit design and layout while maintaining over-voltage protection capability.
Data Source
AI summary
Some exemplary embodiments of a III-nitride switching device with an emulated diode have been disclosed. One exemplary embodiment comprises a GaN switching device fabricated on a substrate comprising a high threshold GaN transistor coupled across a low threshold GaN transistor, wherein a gate and a source of the low threshold GaN transistor are shorted with an interconnect metal to function as a parallel diode in a reverse mode. The high threshold GaN transistor is configured to provide noise immunity for the GaN switching device when in a forward mode. The high threshold GaN transistor and the low threshold GaN transistor are typically fabricated on the same substrate, and with significantly different thresholds. As a result, the superior switching characteristics of III-nitride devices may be leveraged while retaining the functionality and the monolithic structure of the inherent body diode in traditional silicon FETs.