Integrated All-GaN Driver for High-voltage DC-DC Power Converters

This article presents a high-voltage power converter based on an all-GaN half-bridge architecture, incorporating a novel pulse-charging bootstrap circuit. The proposed half-bridge using only E-mode and D-mode GaN transistors integrates the power switches and drivers on the same substrate to suppress parasitic effects and output ringing, thereby improving the overall performance of the converter. The high-side gate driver adopts the E-stacked/D/E-mode (EDE) architecture to directly drive the power transistor's gate with a low-voltage signal, without additional level shifters, simplifying design and reducing propagation delay. Moreover, the architecture exploits GaN's reverse-conducting property as an active diode to charge the bootstrap capacitor, mitigating excessive DC losses and improving overall efficiency. The low-side power transistor is driven by a stack of two D/E-mode devices, with a minimum gate drive voltage of -5 V, preventing false triggering when the low-side driver is turned off. The proposed fully integrated half-bridge is implemented in a 0.5 μm GaN process and simulated in Cadence Spectre in a buck power converter. For an input voltage above 400V, the half-bridge outputs a driving voltage with an operating frequency greater than 1 MHz and generates pulse waves with a rise time and fall time of 50.4 nsec and 52.6 nsec, respectively.