Active Devices

Abstract

In addition to the passive devices described in Chapter 7 most systems will include active elements. These elements will perform various functions such as detection, mixing, power generation and signal control such as electronically controllable attenuation, phase shift and switching. At the heart of these units are the active devices such as diodes and transistors, and their influence on the complete circuit is generally modelled in terms of equivalent circuits for the element. The operation of the basic active devices will now be discussed, along with their equivalent circuits.