Research And Design Of A Buck-Boost Which Applied To Shutdown High Voltage GAN Gate Driver

Gallium nitride(GaN)power devices are rapidly gaining advantages in communications,automotive electronics,radar and wireless charging applications due to their unique advantages in high switching speed and high breakdown voltage characteristics.However,designers are not only looking at these high-end applications,they have begun to continually try to use GaN devices in the design of new portable devices to achieve the superior performance of the next generation of products.However,when the traditional zero-voltage turn-off,positive-voltage-on power drive circuit is applied to high-voltage GaN power devices,the common mode noise crosstalk caused by high dv/dt and di/dt will greatly limit the application of GaN power devices under high voltage.By using a negative-voltage shutdown,a zero-voltage-on drive circuit to drive a depletion-mode GaN power device can improve the common-mode noise immunity of the driver circuit.In order to power the high-voltage GaN driving circuit from a single power supply,it is necessary to design a negative voltage generating circuit in the driving circuit to provide a negative voltage power supply for shutdown the high voltage GaN gate driver.In the background of this research,designing a negative voltage power supply for high voltage GaN gate drive has important research significance.This paper introduces two methods of generating negative voltage power that can be applied to high voltage GaN gate drive negative voltage shutdown,namely,a charge pump and a Buck-Boost circuit.By analyzing the working principle of two negative voltage power supplies,the advantages of two negative voltage power supplies in high voltage GaN gate drive application scenarios are compared.This paper selects Buck-Boost with higher efficiency,continuously adjustable output voltage and higher load capacity.The converter acts as a negative voltage source that drives the high voltage GaN gate drive.Based on this background,this paper designs a Buck-Boost vacuum converter based on constant on-time control: a shutdown time module that samples the average output voltage to control the off-time is designed.A high-speed low-power level shift is designed which consumes the possibility of signal transmission between different power rails in the system.A high-speed current limit comparator circuit is designed,which is control power tube switch timely when the inductor current of the Buck-Boost converter is over-current.A high-speed zero current detection circuit is designed to quickly enter the DCM mode when the inductor current is detected to zero.The Buck-Boost system designed for high voltage GaN gate drive is designed and verified by the 0.35?m BCD process.The simulation results show that the designed Buck-boost vacuum system works normally and has a stable output voltage of-14 V at 12 V input power.When the negative voltage power supply is applied in the high-voltage GaN gate drive,the internal power supply is matched with the power-on sequence,and the high-voltage GaN gate drive can work normally,achieving the expected design goal.