ABSTRACT
A linear amplifier can be described by a two‐port (or similarly, a four‐terminal) device, in which the input voltage and input current are represented, in addition to the output voltage and output current. These variables are sufficient to specify the operation of many different electronic devices, more specifically, linear devices. The hybrid parameter representation is useful in the analysis of linear electronic circuits, such as those with transistors or operational amplifiers. In a general manner, amplifiers can be classified as signal amplifiers or power amplifiers. Power amplifiers aim to couple the maximum energy to the next amplification stage, or to a transmitter, for example. On the other hand, signal amplifiers aim to couple the voltage or current signal to the next stage, for this, they operate with unmatched impedances for the signal to be completely transferred.
