Impact of Parasitic Elements on Power Loss in GaN-based Low-voltage and High-current DC-DC Buck Converter

Parasitic elements have significant impacts on the power loss of GaN-based DC-DC converter. And this situation will be more severe for a converter with low output-voltage and high output-current. This work mainly investigates the impacts of the parasitic elements on power loss in GaN-based low-voltage and high-current buck converter. The parasitic inductance in source terminal of high-side transistor has a relative larger impact on the power loss. However, the power loss induced by the parasitic resistance in low-side transistor takes a large proportion. Furthermore, the presence of parasitic inductance in the return of afterflow may degrade the freewheeling capacity of the anti-parallel diode, or even makes the diode completely ineffective. As a result, the printed circuit board (PCB) with four thickening copper layers and an optimum PCB layout are implemented to minimize the impacts of parasitic elements. The experiment results show that a 12/1.2 volts (output current from 8 amperes to 12 amperes) GaN-based converter with high-efficiency of over 90% is achieved, which delivering an improvement in efficiency of 5% at output current of 15 ampere compared to the previous non-optimization results.