Section D6: BJT Amplifier Applications
In the last several sections, we have extensively studied each of the four basic BJT amplifier configurations and developed analytic expressions for basic amplifier properties. In this section, we are going to compile all this information (not the equations again, don‘t worry!) and discuss uses for each of the configurations based on their characteristics.
To start with, let‘s see what characteristics an ideal amplifier would have. The two-port network representation of Figure 5.2 is given to the right, with the amplifier inside the black box. Each configuration we discussed has its own expression for the characteristics of input and output resistance (Rin and Rout), but in every case, Rin is considered to be parallel to vin and Rout is in series with the load RL. So… an ideal amplifier would have