There are several factors which affect the gate of the MOSFET, and it is necessary to understand the fundamental basis of the device structure before the MOSFET behavior can be explained. This application note details the basic structure of the Trench MOSFET structure, identifying the parasitic components and defining related terminology. It also describes how and why the parasitic parameters occur. With a large variety of topologies, switching speeds, load currents, and output voltages available, it has become impossible to identify a generic MOSFET that offers the best performance across the wide range of circuit conditions. In some circumstances the on-resistance (rDS(on)) losses dominate, and in others it is the switching losses of the transient current and voltage waveforms, or the losses associated with driving the gate of the device. It also has been shown1,2 that the input and output capacitances can be the dominant loss.