723 Power Mosfets

The power MOSFET is a controlled switch similar to the power BJT. The three terminals of the MOSFET are gate, drain, and source, which are analogous to the base, collector, and emitter, respectively, of the BJT. Similar to the power BJT, the MOSFET is a Quadrant I switch allowing forward flow of current and blocking forward voltage between drain and source. The device works as a controlled switch through control of the voltage between gate and drain. The current-voltage characteristics of a MOSFET are illustrated in Figure 7.6a. Unlike the BJT, the MOSFET is a voltage-driven device with much faster switching capabilities. This allows power MOSFET operation at much higher frequencies compared to the BJT, although the available maximum device voltage and current ratings are much smaller than the BJT.

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