A fully integrated GaN-based power IC including gate drivers for high-efficiency DC-DC Converters

In this paper, we present a state-of-the-art integrated GaN power IC capable of operating in a high frequency (MHz) regime. This realizes system size reduction, 60% maximum, of a power IC. The IC consists of two output power transistors (PT) and two gate drivers (GD). The key devices in the IC are normally-off gate injection transistors (GITs) for PT and GD and a normally-on hetero-junction field effect transistor (HFET) for GD. Novel local control of carrier concentration of an identical 2 dimensional electron gas (2DEG) at an AlGaN/GaN interface which made integration of the transistors with such a large threshold voltage difference possible is described. A specially developed post-passivation interconnection process giving low parasitic components is also described. The IC applied to a 12V-1.8V DC-DC converter shows high frequency switching operation well beyond the limit of Si pointing to future improvement in consumer electronics power supply systems.