Transistors
George Domingo · 2020
This chapter explores what happens when we have not two, but three layers of different types of semiconductors. It discusses the pnp- and npn-transistors, and some modifications such as using metals in conjunction with semiconductors to obtain the complementary metal oxide semiconductor transistors. The bipolar junction transistor is a current controlled device, that is, the base current controls the current between emitter and collector. Field-effect transistors (FETs) can be divided into junction FETs (JFETs) and metal-oxide semiconductor FETs (MOSFETs). The main advantage of MOSFETs is that the gate is insulated from the rest of the circuit, thus presenting an almost infinite input resistance. MOSFETs can also work in both the enhancement and depletion modes.