Modelling of maximum power efficiency of charge pump circuits

The loss estimation in a switched-capacitor DC-DC converter has caused much controversy because of the uncertainty of the contribution of device parasitics to the power efficiency of a converter. Beginning from a simple equivalent circuit model, a closed-form solution to the maximum achievable power efficiency of a converter in which both the effects of parasitic resistance and capacitance are taken into account is presented. It has been observed that the peak power efficiency of a Dickson charge pump depends mainly on the equivalent parasitic capacitance of a given technology and its operation mode, which is governed by the choices of the coupling capacitance, on-resistance of the switch, as well as the operation frequency of the circuit.