A MOSFET only, step-up DC-DC micro power converter, for solar energy harvesting applications

In this paper, a step-up micro power converter for solar energy harvesting applications is presented. The circuit is based on a switched-capacitor voltage doubler architecture with MOSFET capacitors, which results in an area approximately eight times smaller than using MiM capacitors for the 0.13μm CMOS technology. In order to compensate for the loss of efficiency, due to the larger parasitic capacitances, a charge reutilization scheme is employed. The circuit uses a phase controller, designed specifically to work with a solar cell, in order to regulate the output voltage to 1.2 V. Electrical simulations of the circuit, together with an equivalent electrical model of a solar cell, show that the circuit can deliver a power of 536.1 μW to the load, while drawing a power of 799.8 μW from the solar cell, corresponding to a maximum efficiency of 67%.