Fully integrated switched-inductor switched-capacitor dual-path DC-DC converter

A fully integrated switched-inductor switched-capacitor (SISC) DC-DC converter is proposed. This converter is designed in such a way that the input voltage can be twice the process allowable voltage without damaging the on-chip transistors. To mitigate large series resistance of on-chip inductors as one of the main challenges in the switched-inductor power supply on chip, two solutions are proposed. By using analytical model of an on-chip inductor, optimal physical dimensions are designed to achieve the desired inductance with minimum series resistance in a small area. Along with the optimization, the dual-path structure of the proposed converter reduces series resistance losses of the on-chip inductor and increases the effective quality factor up to 7 times in duty cycle of 0.8. The proposed converter is implemented in 0.18 mu m standard CMOS process. The circuit converts input voltage of 3.6-0.9 V at the load current of 125 mA with the efficiency of 72.8%. Efficiency enhancement factor reaches 72% at 600 mV output voltage. The achieved current density of the proposed converter is 333 mA/mm(2). By calculating small signal model of the proposed converter and designing a suitable feedback loop, an appropriate transient behavior was proved