High-Conversion-Ratio Switched-Capacitor Step-Up DC-DC Converter

A closed-loop scheme of high-conversion-ratio switched-capacitor (HCRSC) converter is proposed based on pulse-width-modulation (PWM) control for step-up conversion and regulation. In the HCRSC, there are totally 4 sets of series-parallel SC cells between source Vs and output Vo, where each cell has 3 capacitors. With the capacitors charging in parallel and discharging in series cyclically, each cell will be a small converter of triple voltage gain. And by the 4 cells working complementarily, the main function is to boost Vo voltage up to 3x3 times of Vs at most. In addition, this SC converter needs no magnetic element, e.g. inductor/transformer, so I.C. fabrication will be promising for VLSI applications. Here, the closed-loop HCRSC is simulated by OrCAD Spice, and some cases are included as: voltage conversion and output ripple percentage, output robustness against source variation, and regulation capability of converter with loading variation. The results are illustrated to show the efficacy of the proposed scheme.