GaN-based SEPIC DC-DC converters: design and performance comparisons

The need for more efficient and compact DC-DC converter design has directed recent research to the use of Gallium Nitride (GaN) High Electron Mobility Transistors (HEMTs), capable of achieving higher switching speeds, in place of Silicon (Si) Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) which are nearing their theoretical maximum performance limit. The Single-ended Primary Inductor Converter (SEPIC) is one of the simplest designs of DC-DC converter with a relatively low component count, yet is capable of both buck and boost operation. A GaN-based current-regulated SEPIC, is therefore attractive for applications such as in solid state lighting; which is the prime focus of this research. This thesis reports work conducted to evaluate GaN HEMT’s performance against a Si FET with matching specifications. This comparison was carried out over a range of frequencies and duty cycles. The results of this work show a marked improvement in performance efficiency of GaN in comparison to Si over MHz frequency range. Moreover, a GaN-based SEPIC using discrete components having current regulation was developed. The underlying idea for building this circuit is to develop a regulated simple and efficient power supply, capable of being integrated for solid state lighting applications in the future.