10.1. Power Bipolar Junction Transistor (BJT)
The power bipolar junction transistor (BJT) was the first semiconductor switch that was used for the implementation of power electronics switching topologies. There are two types of power transistors, the npn and the pnp, and are shown in Fig. 10.1(a) and (b), respectively. As shown in Fig. 10.1 the transistor is a three layer device and has three terminals: the base (B), the emitter (E), and the collector (C).