Analysis of a Switched-capacitor DC-DC Converter for Low-Power Applications

This thesis proposes an analysis of a fully integrated switched-capacitor DC-DC converter as well as the dedicated control loop. This converter aims to step down a pre-regulated input voltage of 1.8 V to an output voltage which can range from 0.6 V to 1.2 V and is able to deliver a maximum current of 25 mA at each operative condition. The control loop is implemented using a pulse-frequency modulation (PFM) technique supported by further additional control techniques which help to keep the performances high. In the first part the major advantages of the capacitive converters are illustrated and compared to the inductive converters, especially for integrated applications. Then, the analysis section can be found in which the solutions of the state of the art are analyzed in order to build a suitable converter's model which is able to fulfill the specifications. In the control loop part, the main control techniques proposed in literature are analyzed and the dynamic model of the converter is derived in order to design a suitable regulator for the PFM operation. Besides, some ancillary functions are also discussed and analyzed, such as the start-up circuit and an overcurrent protection circuit. Finally, some simulations in a high-level environment such as Simulink/Plecs are carried out in order to verify the correctness of the analytical models.