Power Electronics and Motor Drive Systems

10.2. Power Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET)

The metal-oxide-semiconductor field effect transistors (MOSFETs) are semiconductor switches that can be used for low power conversion applications and high switching frequencies. In contrast with the BJT the MOSFETs are voltage driven and not current driven, and they exhibit high current gain. Fig. 10.11(a) and (b) shows the cross sections and the symbols of an n-channel and p-channel MOSFET. The MOSFET has three terminals which are the gate, the drain and the source. The operation of a p-channel MOSFET is shown in Fig. 10.11(c).

If a positive drain-source voltage V_DS and a gate-source voltage V_GS below the gate-source threshold voltage level V_GS(th) is applied, then only a ...