This paper explains why and how the very same circuit (a transistor circuit in CS connection) is able to perform multiple applications depending on the use of the transistor in different operating regions. Families of transfer characteristics of the circuit are used to deduce the possible applications. In this way, the emphasis is transferred to understanding the intrinsic operation of a circuit, which opens the perspective for multiple applications, as opposed to the traditional approach, where the emphasis is placed on circuit applications.
