A High Peak Output Power and High Power Conversion Efficiency SIMIMO Converter Using Optimal on-Time Control and Hybrid Zero Current Switching for Energy Harvesting Systems in IoT Applications

This article proposes a single inductor multi-input multioutput (SIMIMO) converter with high peak output power and power conversion efficiency for energy harvesting systems in Internet of Things (IoT) applications. The proposed SIMIMO converter consists of inputs with four harvesters and a battery, and outputs with 1.8 V output, 3.3 V output, and a battery. The optimal on-time control method is proposed to optimally adjust the on time required to energize the inductor, thus increasing the peak output power to cover a wide distance range. In addition, the hybrid zero-current-switching (ZCS) method is proposed to adaptively calibrate the offset of the ZCS comparator, thus improving the power conversion efficiency. The proposed SIMIMO converter is fabricated using 0.18-μm standard bipolar-CMOS-DMOS (BCD) process technology with 1.8- and 5-V devices. The measurement results show that the peak output power is achieved to be 462 mW, and the peak power conversion efficiencies at 1.8 V output, 3.3 V output, and battery are 89.2%, 84.5%, and 86.4%, respectively. Moreover, the quiescent current of the power management controller, which controls the proposed converter, is achieved to be only 1.6 μA. Therefore, the proposed SIMIMO converter is suitable for energy harvesting systems in various IoT applications.