INVESTIGATION OF PARASITICS IN POWER CIRCUITS SWITCHED WITH CASCODE GAN HEMTS

Nikita Hari, Florin Udrea

Abstract: Gallium Nitride (GaN) devices due to its superior material properties over Si has the potential to provide better system level performance when integrated into power electronic applications. These fast switching devices are continuously evolving in the market with 600 V devices getting commercialized and manufacturers coming up with different variants of normally-off devices to completely exploit the wondrous properties of this novel material. The growing acceptability of these devices has seen a strong interest in cascode structures. However, there is a lack of understanding of the issues caused by these nearly ideal devices when used in real circuits. Therefore, this paper is aimed at investigating the influence of parasitic inductances and capacitances that causes unexpected behavior in cascode GaN based half-bridges. This problem is addressed by performing detailed theoretical analysis and Pspice simulations to formulate design rules. These predictions are then experimentally validated by designing and demonstrating 1 kW, 500 KHz GaN half bridge prototypes using different gate drives. The novelty of this paper lies in providing a holistic approach to the instability issues in cascode GaN high electron mobility transistor (HEMT) based half-bridge circuits caused due to parasitics of the device, package and the PCB layout.

Keywords: Gallium Nitride(GaN), HEMT, Cascode, Half-Bridge, Power Converters, Parasitics.

DOI: https://doi.org/10.15623/ijret.2016.0534001