Integrated charge pumps: A generalised method for power efficiency optimisation

Abstract

Charge pumps (CPs) represent the most common solution for the implementation of fully integrated DC-DC converters. In fact, as opposed to buck/boost DC-DC converters, that need at least an external inductor, charge pump circuits do not require any external component. However, the achievable power efficiency of these circuits is typically significantly lower than power efficiency of buck/boost DC-DC converters. In this study, we develop a general mathematical model of CPs, aiming to provide basic design considerations for power efficiency optimisation. A quality factor for achievable power efficiency is proposed together with guidelines for the design of efficiency-optimised CPs under the constraint of given output voltage and current values.