Hard switching speed improvements in GaN-based synchronous buck converters

In designing high efficiency, large step down buck converters, the power semiconductors contribute a significant loss mechanism through switching losses. Minimizing these losses can be achieved by running at lower frequencies, decreasing the actual switching time, or performing soft switching. However, soft switching converters introduce extra components, which can impact reliability, cost, and size of the final converters. Therefore, extremely rapid hard switching is preferable to soft switching converters. This paper proposes a new layout technique for low parasitic inductance paths using commercially standard PCB specifications for very fast switching speeds of GaN power devices in flip-chip packages resulting in a highly efficient (>94%) hard switching 12-1 V synchronous buck converter. The proposed technique is experimentally verified at output loads from 4 - 20 A and achieves less than 5 ns switching times.