5-Level buck converter with reduced inductor size suitable for on-chip integration

Abstract

In this paper, a 5-level buck 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. The 5-level buck converter can work at different operation regions covering wide range of output voltage values. By reducing the voltage difference at the inductor input, the 5-level buck converter can use smaller inductor compared to both 3-level and conventional buck converters which makes it more suitable for on-chip DC-DC conversion. A test circuit has been implemented in TSMC 65nm technology using 0.5nH on-chip spiral inductor and simulation results show better performance as compared to conventional and 3-level buck converters. For same switching frequency and inductor size, the 5-level buck converter achieves more than a 15% efficiency improvement over a 3-level buck converter at certain output voltage ranges.