Capacitor Selection and Sizing in Linear and Exponential Integrated Charge Pumps

This paper presents a method for optimizing the sizes of the flying capacitors when using different types of devices in the same integrated charge pump. Higher power density can be achieved by using multiple device types rather than a single type rated for the capacitor with the highest working voltage. Analytic models for the linear and exponential charge pumps are used to estimate the improvements and reveal design tradeoffs. Simulations with parasitic effects and a case study highlight the performance differences to inform the choices of the designer.