GaN Transistor Gate Circuit for Normally-Off Switching
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Solution Overview
Problem
Converting GaN power devices from normally-on to normally-off type poses challenges, including the inability to adjust gate drive capability, requiring dedicated negative power supplies and gate drivers, and a trade-off between preventing erroneous ON states and standby power consumption.
Innovation Solution
A semiconductor device configuration that includes a first and second circuitry connected to a power supply and ground voltage, with a diode connected between the transistors, allowing for passive operation without external input signals, controlling the voltage applied to the transistors to prevent simultaneous switching and reduce standby power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a circuit converts GaN transistors from normally-on to normally-off type, then the transistor can operate in normally-off mode, but the gate drive capability cannot be adjusted by the conversion circuit
Solution Approach 1:
The conversion circuit automatically detects the power supply voltage state and self-adjusts the gate drive voltage without requiring external control signals. The circuit monitors its own operating conditions and autonomously switches between normally-on and normally-off modes, eliminating the need for external adjustment while maintaining adaptability
Solution Approach 2:
The circuit incorporates feedback mechanisms where the output state influences the gate drive voltage. By monitoring the power supply voltage and transistor state, the circuit dynamically adjusts the gate voltage to maintain proper operation mode, enabling both reliable normally-off operation and adaptive gate drive control
2Reliability
If a dedicated negative power supply circuit and gate driver are used, then normally-off operation is achieved, but the device complexity increases
Solution Approach 1:
The conversion circuit is designed to perform multiple functions using a single integrated structure. It simultaneously provides voltage detection, gate drive control, and mode switching capabilities without requiring separate dedicated circuits for each function, thereby reducing overall device complexity while maintaining normally-off operation reliability
Solution Approach 2:
The patent merges the voltage detection circuit, gate drive control, and transistor switching functions into a single integrated conversion circuit. By combining these previously separate components into one unified structure, the circuit complexity is reduced while achieving reliable normally-off operation
3Use of energy by stationary object
If the gate driver power supply is turned off to reduce standby power, then power consumption decreases, but the trade-off between erroneous ON prevention and standby power is large
Solution Approach 1:
The conversion circuit autonomously monitors the power supply voltage state and self-regulates the gate drive voltage without requiring continuous external power or control signals. This self-service capability allows the circuit to maintain reliable normally-off operation even when the gate driver power supply is turned off, achieving both low standby power consumption and robust erroneous ON prevention
Solution Approach 2:
The circuit is designed with inherent protection mechanisms that prevent erroneous ON states before they can occur. By structuring the voltage detection and gate control to inherently block spurious turn-on signals, the circuit maintains reliability without requiring continuous active power, enabling the gate driver power supply to be turned off during standby
Data Source
AI summary
A semiconductor device that normally-off drives a first transistor that normally-on drives, the semiconductor device includes a first circuitry, a second circuitry, and a first diode. The first circuitry that is connected with a power supply voltage and a ground voltage, detects the power supply voltage, and outputs a transition state of the power supply voltage. The second circuitry that is connected with the power supply voltage, the ground voltage, the first circuitry, and a second transistor, and outputs a drive voltage of a second transistor connected in series with the first transistor, based on an output of the first circuitry. The first diode having an anode connected with a drive terminal of the first transistor and a cathode connected with an output terminal of the second transistor.