Channel current analysis of GaN HEMTs with source sense pin in DC/DC boost converters

Abstract

The breakdown strength and electron mobility of gallium nitride (GaN) are almost ten and three times higher than those of the silicon devices. Wide band-gap devices have a higher thermal conductivity, higher switching frequency capability, lower on-state resistance and lower power dissipation. Detailed analytical models in the electrical network and channel current variations of these devices during switching intervals are still under investigation. The energy loss and heat dissipation on a power converter can be precisely estimated if the operational modes and the corresponding mathematical models of the device are accurately obtained. Depending on the instantaneous values of the channel current and voltage drops on the components computed from the model, the power dissipation and thermal response can be examined. Prediction of the switching losses of a GaN high electron mobility transistor (HEMT) with a source sense pin can be performed using the instantaneous variation of channel current. In this paper, a detailed analytical model including the stray inductances and parasitic capacitors is derived to obtain the channel current of GaN HEMTs with a source sense pin. The turn-on and turn-off transient energy losses during the switching of a single GaN HEMT device can be computed from the analytical model proposed in this paper using the channel current and drain-source voltage. Results of the derived analytical model, SPICE simulations and experimental work on the DC/DC boost converter are compared.