Freewheel charge-pump controlled single-inductor multiple-output step-up DC-DC converter

Abstract

This paper presents a freewheel-charge-pump-controlled design for a single-inductor multiple-output (SIMO) DC-DC Converter. By applying the freewheel-charge-pump-controlled (FCPC) technique, the freewheel switching time is reused, and two extra charge-pump outputs are provided by time recycling, with no cost in time sequences. The converter has two step-up outputs and two charge-pump outputs that can be higher or lower than the input supply. The converter utilizes a 1 mu H inductor, 4.7 mu F charge-pump capacitors and 33 mu F output capacitors at a frequency of 1 MHz. The proposed converter shows low cross-regulation and achieves a maximum loading current of 70 mA. Fabricated in a 0.18-mu m CMOS process, the proposed circuit occupies 1.3 x 1.3 mm(2). Experimental results demonstrate that the converter successfully generates four well-regulated outputs with a single inductor. The supply voltage ranged from 1.6 to 2.5 V and the load regulation performance was 0.08, 0.05, 1.7, and 1.9 mV/mA for V-O1, V-O2, V-O3 and V-O4, respectively.