A Resonant Synchronous Gate Driver for GaN e-HEMTs

Abstract

Gallium nitride based enhancement-mode high electron mobility transistors (e-HEMTs) are allowing power converters achieve power densities and efficiencies beyond what has ever been possible with silicon MOSFETs. As e-HEMTs facilitate converters with higher switching frequencies and as unit efficiencies rise, so does the emphasis on having faster and more efficient gate drivers. The conventional totem pole gate driver dissipates the entire gate charge every switching transition, is highly sensitive to parasitic inductance, and has limited control over switching speed. These issues are even greater with e-HEMTs that are capable of switching in under one nanosecond and have much more sensitive gates than silicon MOSFETS. By its very nature, a current source gate driver has control over the rate of change of gate voltage, facilitating faster transitions with lower hard switching losses, and because it is derived from an inductance it has the potential of recovering charge stored in a gate that would otherwise be dissipated. This thesis will introduce and demonstrate the performance of a novel resonant synchronous gate driver applied to a push-pull Class E amplifier for wireless power transfer.