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Three-Level Driving Method for GaN Power Transistor in Synchronous Buck Converter

Fig. 1. V-I curve of GaN power transistor (EPC 1015).
The emerging Gallium-Nitride (GaN) based power transistors offer the potential to achieve higher efficiency and higher switching frequencies than possible with Silicon MOSFET's. This paper first discusses the enhancement-mode GaN device characteristics. The high reverse conduction voltage of the GaN devices makes it not preferred for synchronous converters. A three-level driving method is proposed to overcome the high reverse conduction loss issue of the GaN power transistor. Finally, a 12V to 1.2V Synchronous Buck converter with a full load current of 20A is built to verify the proposed method. The experimental results show that the proposed method is necessary and effective for efficiency improvement in high switching applications of a GaN power transistor.

Fig. 2. 3-level driving method for SR buck converter.
Fig. 3. Schematic of 3-level driving method for buck converter.
Fig. 4. Efficiency comparison of diode vs 3-level at different frequency.