Floating power supply rail applicable to GaN high-speed gate driving circuit

Abstract

The invention relates to a floating power supply rail applicable to a GaN high-speed gate driving circuit, and belongs to the technical field of power management. With the design of dual floating power supply rails, a GaN power switch device can work within a safety voltage, and a low-voltage-to-high-voltage potential displacement circuit has enough dynamic range. A high-voltage-to-low-voltage potential displacement circuit, a voltage clamping circuit, a logic control circuit and a first floating power supply rail generation circuit form a closed loop, a BST for generating a first power supplyrail is used as a power supply rail of a buffer circuit in the GaN high-speed gate driving circuit, and a gate source voltage of the GaN power switch device can be enabled to be within a safety range; and a second floating power supply rail generation circuit forms a closed loop, a BSTA for generating a second power supply rail is used as a power supply rail of the low-voltage-to-high-voltage potential displacement circuit in the GaN high-speed gate driving circuit, and the GaN high-speed gate driving circuit can be enabled to have enough dynamic range.

Description

technical field [0001] The invention belongs to the technical field of power management, and in particular relates to a floating power rail suitable for a GaN high-speed gate drive circuit. Background technique [0002] With the development of power electronics in recent years, half-bridge drive circuits are developing towards high power and high frequency, which also brings new requirements to the selection of power tubes and circuit design. Traditional half-bridge drive circuits mainly use silicon power transistors as the power stage. In contrast, GaN power switch devices (such as GaN HEMT) have good physical characteristics such as high voltage resistance and no reverse recovery time, so GaN power switches are used. The half-bridge gate drive circuit of the device has excellent characteristics such as high speed and high power density. However, when an enhanced GaN power switching device (GaN HEMT is used as an example below) is used as the power tube of the half-bridge ...

AI Technical Summary

Problems solved by technology

But because the bootstrap capacitor C boot The voltage difference between the upper and lower plates V BST -V SW Clamped within 5.5V to ensure safe operation, and the dead time power stage bias voltage V SW large negative value, the bootstrap capacitor C boot coupling effect, the floating power rail BST level will follow the power stage bias voltage V SW Entering the negative voltage is much lower than 5V, which brings new problems: 1. The dynamic range of the low-voltage to high-voltage level shift circuit (Level Up) that connects the power tube control circuit and the low-voltage logic circuit on the bridge is not enough (low-voltage to high-voltage level shift circuit). The power rail of the high-voltage level shift circuit is generally a floating power rail (BST and chip ground), which causes the response speed of the low-voltage to high-voltage level shift circuit (Level Up) to fail to meet the high-speed requirements, and the transmission delay of the driving signal increases; 2. After The threshold level of the stage logic circuit will decrease with the synchronous decline of the floating power supply rail BST and the low voltage power supply rail SW potential during the dead time, and at the same time, due to the reduction of the dynamic range of the low voltage to high voltage level shift circuit (Level Up) It will cause the amplitude of the driving signal to decrease after passing through the level shift. These two phenomena will cause the input signal to not be recognized by the subsequent logic circuit during transmission and signal loss will occur.

The above problems have brought difficulties to the design of high-speed and high-power half-bridge gate drive circuits suitable for GaN power switching devices, making it difficult to implement GaN power switching devices that can work within a safe voltage and low-voltage to high-voltage level shift circuits ( Level Up) floating rail with sufficient dynamic range

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