A 28nm FDSOI integrated reconfigurable switched-capacitor based step-up DC-DC converter with 88% peak efficiency

Abstract

This paper presents a fully integrated, reconfigurable switched-capacitor based step-up DC-DC converter in a 28nm FDSOI process. Three reconfigurable step-up conversion ratios (5/2, 2/1, 3/2) have been implemented which can provide a wide range of output voltage from 1.2V to 2.4V with a nominal input voltage of 1V. We propose a topology for the 5/2 mode which improves the efficiency by reducing the bottom-plate parasitic loss compared to a conventional series-parallel topology, while delivering the same amount of output power. Further, the proposed topology benefits from using core 1V devices for all charge-transfer switches without incurring any voltage overstress. The converter can deliver load current in the range of 10 μA to 500 μA, achieving a peak efficiency of 88%, using only on-chip MOS and MOM capacitors for a high density implementation.