The trend in Intermediate Bus Converter (IBC) is increasing output power demands and higher operating frequencies, while the appearance of GaN devices will improve the power density of the converter possibly. This paper analyzed the high frequency characteristics of GaN devices and its advantages at high frequency applications. Owing to difficulties in designing driver circuit and layout, the paper designs the key parameters in the driver circuit. An optimized design of resonance parameters in LLC topology aiming for improved efficiency tradeoff between the dead time and shunt branch numbers is investigated. Then, an improved matrix transformer which would enhance the performance of the traditional transformer and decrease the leakage inductor and eddy current loss is proposed. Finally, a 300 W LLC prototype is designed on mentioned approach and some experiments have been made.