Adaptive On-Time-Controlled PFM Boost Converter with a Below-Threshold Startup Voltage

Abstract

A high-efficiency pulse-frequency modulation (PFM) boost DC–DC converter with adaptive on-time (AOT) control method is proposed. A novel three-step startup procedure is proposed and applied on the boost converter, which makes the converter start up with a below-threshold voltage. Besides, adaptive on-time control method can reduce the output ripple dramatically. The proposed integrated boost converter is designed in an SMIC 0.18-[Formula: see text]m standard CMOS process and occupied a chip area of [Formula: see text][Formula: see text]mm2 without any low-[Formula: see text] MOSFETs. In the adopted process, the threshold voltages of PMOS and NMOS are [Formula: see text]0.45[Formula: see text]V and 0.48[Formula: see text]V, respectively. The simulation results show that the proposed converter can start up successfully at the input voltage of 0.25[Formula: see text]V, the output voltage is 1.8[Formula: see text]V with the ripple less than 33[Formula: see text]mV, and the peak efficiency can be up to 94.7%.