Efficiency optimization of multi-mode monolithic DC-DC converters

This paper presents a detailed study of the power losses and efficiency optimization of a multi-mode Buck converter. The gate capacitive losses are compared to the conduction losses in order to find the optimum MOSFET V_GS that maximizes the converter efficiency. The developed models are compared to the simulation of two MOSFET families and a simple circuit implementation and control strategy is developed that allows achieving near optimum results. The obtained results for a 350mA Buck show that the average efficiency optimization is 11.7% for load currents below 10mA using the proposed methodology.