1.5 Junction Field Effect Transistor—JFET

Here is the second active device in the series. Its fundamental difference with respect to the BJT is the fact that the transistor effect is achieved by an electric field which is controlling the output current. So, we introduce the first component of the family of field effect transistors (FET). Since there is no need for a current to control the output, these components exhibit very high resistance between the input terminals. On the other side, while with reduced transconductance compared with BJT, they exhibit high output resistance also. We will deliver here all the necessary information to basically understand the functionality of the new component and, of course, to its applicability. Note the part of Appendix 1B where some SPICE simulations are given with the aim to clarify some aspects related to the nonlinearity and dynamic behavior of this component, please.