A Gallium Nitride Switched-Capacitor Circuit Using Synchronous Rectification

The physical characteristics of gallium nitride (GaN) make it theoretically superior to silicon (Si) in such aspects as the temperature of operation, switching speed, breakdown voltage, and efficiency. While much research has been conducted on GaN devices, the discussion of third-quadrant operation is limited. Furthermore, the merits of GaN transistors, particularly their fast switching speed and low on-resistance, make them suitable for switched-capacitor circuits. This paper demonstrates the ability of a GaN transistor to function as a synchronous rectifier in a switched-capacitor circuit. A 500 W GaN-based voltage doubler capable of achieving zero-current switching is presented with supporting experimental results. This circuit achieves peak efficiencies of 97.6% and 96.6% while switching at frequencies of 382 and 893 kHz, respectively.