98.9% Efficiency Fully-integrated GaN Driver for Underwater Wireless Charging Application

This paper proposes a fully-integrated Gate Driver with on-chip GaN power transistors for the application of underwater wireless charging circuit. Because of the absense of PMOS transistor in the GaN process, the novel Comparator, Voltage Reference circuit, Dead-time Generator, Short-pulse Generator, and output Buffer implemented using D-HEMT and E-HEMT are proposed in this work to improve the performance and the efficiency. The novel Comparator is used for generating the PWM control signal for adjusting the output power. The proposed Dead-time and Short-pulse Generator are used to prevent the high-side and low-side transistors conducting simultaneously. The novel Voltage Reference circuit is to provide a stable DC voltage for the Voltage Regulator at all PVT corners. The novel output Buffer could drive the integrated GaN power transistors efficiently by using the E-HEMT as the pull-high element. The proposed design is implemented with TSMC 0.5 μm GaN process. The chip area is 3217.55 × 3709.25 μm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>. The simulation results present the proposed design with an output slew rate of 76.2 V/ns, an efficiency of 98.9%, and an output power of 62.5 W.