Transistors

Abstract

The second kind of active electronic device is the transistor, shown in diagrammatic form in figure 2.1. Two types of transistor exist, these are npn and pnp as shown in figures 2.1a and b respectively, with the carriers, ions, current flow and hole flow. This kind of sandwiched construction applies to the junction transistor; modern transistors are manufactured using integrated circuit techniques (described in chapter 8) but the basic operation is very similar to that described here. Two types of carrier are present inside the junction transistor in a similar way to the pn junction diode and so

junction transistors are one of the family of bipolar transistors. A further family of transistors exists — the unipolar transistor family — including the field-effect transistor and the unijunction transistor; UJT operation is vastly different and is not described here.