Gate Driver with Short Inherent Dead-Time for Wide-Bandgap High-Precision Inverters

This work introduces a novel gate driver for use with wide-bandgap devices in high-power, high-precision applications. As power amplifiers move to higher operating frequencies, the dead time becomes a significant portion of the overall switching period, resulting in reduced control precision and increased output distortion. The developed driver allows to minimize the dead time inserted between the switching actions of a half-bridge. A prototype using 650 V gallium nitride transistors is developed to evaluate the concept. A low-cost digital isolator connects the high and low-side drivers and prevents cross conduction. As long as one switch is conducting, the other is prevented from turning on. This automatically ensures a minimal dead time determined by the isolators propagation delay. Each driver is powered by an isolated unipolar supply and a differential drive scheme provides negative gate-source voltages to safely turn off the transistors despite high switching speeds. The prototype is tested in a double pulse setup at 400 V and reaches dead times as low as 14 ns.