Five-level hybrid DC-DC converter with enhanced light-load efficiency

In this paper, a 5-level hybrid converter is proposed. The circuit structure and the working principle are illustrated. The circuit is capable of providing five different voltage levels at the inductor input with the help of two flying capacitors. By reducing the voltage difference at the inductor input, the 5-level buck converter can use smaller inductors as compared to both 3-level and conventional buck converters which makes it more suitable for on-chip DC-DC conversion. Simulation results on TSMC 65nm technology using 0.5nH on-chip spiral inductor show that the 5-level hybrid converter achieves more than 15% improvement in efficiency over a 3-level buck converter at certain output voltage ranges. A test PCB is also implemented for verification of the functionality and experimental measurements show that the 5-level hybrid converter can achieve better efficiency as compared to conventional and 3-level Buck converters especially at low load currents.