A comparison of GaN-based power stages for high-switching speed medium-power converters

Three GaN-based buck switching power stage architectures are implemented using discrete GaN High Electron Mobility (HEMTs) devices and compared with respect to efficiency, switching speed (2 to 10MHz), and power conversion ratio for medium-power applications. The three presented power stage architectures are: a single-stage buck, a multi-phase buck with 2 phases, and a stacked interleaved configuration. This work theoretically evaluates the various architectures, details the designs, and presents the measurement results. All of the implemented power stages achieve over 80% peak efficiency, and switching speeds up to 10MHz with high conversion ratio from 24V input to 5V output. The use of GaN power devices in the power stage for such applications provides small form factor, high current density, and high efficiency at high switching speeds. Each architecture has its inherent advantages for non-isolated large conversion ratio point-of-load applications, which will be discussed in this work.