Highly-Efficient MHz-class Operation of Boost DC-DC Converters by Using GaN Transistors on GaN with Reduced RonQoss

We fabricate newly-developed GaN transistors on GaN substrates with reduced RonQoss (Ron : on-state resistance, Qoss : output charge), which enable 1MHz switching operation with smaller conduction losses compared with the counterparts fabricated on Si substrates. When the GaN transistor fabricated on the GaN substrate is employed in a boost DC-DC converter, its peak efficiency reaches 98.2% at the output power of 600W, in which the device-related loss is reduced by 45% compared with the case conventional GaN transistors on Si substrates are employed.