A single-inductor MIMO buck-boost converter with inductor-peak-current PFM control for multiple energy harvesting

This paper presents a single-inductor four-input-three-output buck-boost converter which can harvest energy from three sources simultaneously, with a wide range of input voltage from 0.2V to 3V. A control strategy combining the inductor-peak-current (IPC) controls and pulse-frequency modulation (PFM) is proposed to suit for the muli-sources energy harvesting. The IPC control is used to improve the efficiency and decrease the output voltage ripple. The PFM is utilized to regulate the outputs as well as make the three sources around their maximum power point (MPPT). The converter is designed and verified in the CSMC 0.18um process. Simulation results show that the efficiency of the converter is no less than 74% under the wide range of input voltage with load varying from 10 uW to 1 mW.