Toward a Minimum-Operating-Voltage Design of DC-DC Charge Pump Circuits for Energy Harvesting

This paper expands upon the circuit model of DC-DC charge pump circuits to include the reverse leakage current which becomes significant at extremely low voltages in energy harvesting. The paper proposes a design flow to determine all the design parameters of charge pump circuits operating in sub-threshold region such as a clock frequency, stage capacitor size, rectifying device size and number of stages based on the model. The methodology is demonstrated and verified by SPICE simulation. By using the proposed flow under given conditions, circuit designers can numerically obtain trade-offs between power supply voltage, circuit area and power efficiency of DC-DC charge pump circuits to design energy harvesting systems