Modeling low-voltage power MOSFETs as synchronous rectifiers in buck converter applications

Abstract

This paper proposes a two-dimensional model of low-voltage power MOSFETs, which are suitable for synchronous rectifier applications. First of all, the device has been characterized by measuring the output (I-V) and transfer characteristics, the capacitance curves (C-V), the breakdown voltage, the body-drain diode characteristic (I-V) and the reverse recovery performance. Hence, a device model was derived through a two-dimensional (2D) process simulator. Finally, advanced 2D mixed device and circuit simulations have been carried out finding a good agreement with the experimental results. The aim of this work is to give a contribution to the analysis and design of such devices, looking for the actual power converter applications, by exploiting the enormous potential of modern CAD tools. Simulation runs relative to a synchronous-rectifier buck-converter have been performed too, in order to verify the correctness and validity of the MOSFET model, and also to investigate the internal dynamics of the main switch and the synchronous rectifier during the behavior on the application.