GaN-Si Cascode Semiconductor Device Overvoltage Protection
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Solution Overview
Problem
Existing semiconductor devices using GaN-based transistors face challenges in achieving normally-off operation safely in power circuits handling high voltages, as they tend to experience breakdown or degradation due to overvoltage at the connection point between normally-on GaN-based and normally-off Si transistors.
Innovation Solution
A semiconductor device configuration that includes a normally-off transistor, a normally-on transistor, a capacitor, diodes, and a coil component, where the normally-on transistor performs OFF operation before the normally-off transistor when switching from ON to OFF state, and includes a second diode connected between the voltage terminal and the drain to suppress overvoltage, ensuring reliable operation and energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a normally-on GaN-based semiconductor transistor is cascode-connected to a normally-off Si transistor to achieve normally-off operation, then the power circuit can achieve normally-off operation required for safety, but overvoltage occurs at the connection point between the two transistors causing breakdown or degradation
Solution Approach 1:
A capacitor is introduced as an intermediary component between the normally-on GaN-based transistor and normally-off Si transistor. This capacitor couples the two transistors and enables controlled signal transmission while preventing direct overvoltage transmission to the connection point, thus protecting against breakdown while maintaining normally-off operation capability
Solution Approach 2:
A diode is connected in parallel with the capacitor to provide beforehand protection. When overvoltage occurs at the connection point, the diode conducts to clamp the voltage, cushioning the harmful effect before it can cause breakdown or degradation of the transistors
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
This configuration prevents overvoltage at the connection point, enhances the reliability of the semiconductor device, and improves energy efficiency by allowing charge to be released back to the power source during startup or restart, thereby reducing the risk of malfunction and maintaining high performance.
Implementation Method 1
a first capacitor provided between the gate terminal and the second gate
Implementation Method 2
a first diode having a first anode electrically connected to the first capacitor and the second gate, and a first cathode electrically connected to the first source
Implementation Method 3
a coil component provided between the voltage terminal and the second drain
Data Source
AI summary
A semiconductor device according to an embodiment includes a normally-off transistor having a first drain, a first source electrically connected to a source terminal, and a first gate electrically connected to a gate terminal, a normally-on transistor having a second gate, a second source electrically connected to the first drain, and a second drain electrically connected to a voltage terminal, a first capacitor provided between the gate terminal and the second gate, a first diode having a first anode electrically connected to the first capacitor and the second gate, and a first cathode electrically connected to the first source, a coil component provided between the voltage terminal and the second drain, and a second diode having a second anode electrically connected to the first drain and the second source, and a second cathode electrically connected to the coil component and the voltage terminal.