Using MOSFET Controllers to Drive GaN E-HEMTs

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This article was originally published in Bodo’s Power Systems August 2019 issue by By Yajie Qiu, Senior Power Electronics Applications Engineer, and Juncheng (Lucas) Lu, Applications Engineering Manager, GaN Systems. A small portion is available here and the rest can be read along with supporting graphics and charts in the PDF below.

Before gallium nitride (GaN), the silicon (Si) MOSFET was the standard for power in adapter applications for decades. As a result, many of the existing controllers in the marketplace, including power factor correction (PFC) and DC-DC controllers, have already integrated silicon drivers into the controller chip. These controllers have proven to be a cost-effective and complete solution. However, the poor figure-of-merit (FOM) of Si MOSFETs limit the controller’s capability of high switching frequency performance to meet the requirement of high-power density vital to modern power systems.

GaN power transistors have demonstrated high-frequency performance advantages over Si MOSFETS for several years and continue to make significant advancements, including improving ease of driving the power transistor. Enhancement mode GaN (E-HEMTs) are driven with positive voltage between the gate and source, similar to N-channel Si MOSFETs, provide a familiar solution for driving the devices. GaN Systems has a solution to easily use the MOSFET controller 12 V output voltage to drive the GaN 7 V gate input without the need of an external or integrated additional driver….