Analytical Study of Multi-stage Switched-Capacitor Voltage Boost Converter for Ultra-low Voltage Energy Harvesting

An analytical study of a multi-stage switched-capacitor (SC) voltage boost converter (VBC) for ultra-low voltage energy harvesting is presented. Because the output impedance of the VBC plays an important role in the VBC's performance, we developed an analytical model to achieve a highly efficient VBC. In our proposed method, we focus on currents flowing into input and output terminals of each stage and model the VBCs using switching frequency f, charge transfer capacitance Cf, and load capacitance CL. A comparison between simulated and calculated results showed that our model can estimate the output impedance of the VBC accurately. Our model is useful to compare the relative merits of different types of multi-stage SC VBCs.