Single-input GaN gate driver based on depletion-mode logic integrated with a 600 V GaN-on-Si power transistor

This work presents a monolithically-integrated power circuit with a single control input gate driver based on depletion-mode logic and a 600 V, 150 mΩ power HEMT in GaN-on-Si technology. The gate driver final-stage is a push-pull circuit, in which the pull-up transistor is indirectly driven through a depletion-load logic inverter, whereas the pull-down transistor is directly driven by the single external control input. Measurements of soft- and hard-switching turn-on transitions in an inductive-load half-bridge at 300 V/ 4 A demonstrate controllability of the turn-on speed by adding an external speedup resistor in parallel to the depletion-load. Gate-charge measurements show a 25-fold reduction of external pre-driver drive capability requirement during a 400 V turn-on transition, since the main power transistor gate-charge (8.5 nC)-related losses are provided and dissipated within the GaN power device, and only the pull-down gate driver transistor gate-charge of 0.34 nC has to be provided externally by the pre-driver circuit.