ABSTRACT
Controlled sources generate a voltage or current whose value depends on, or is controlled by, a voltage or current that exists at some other point in the circuit. Four such sources exist: (1) voltage-controlled current source (VCCS), (2) voltage-controlled voltage source (VCVS), (3) current-controlled current source (CCCS), and (4) current-controlled voltage source (CCVS). In an ideal controlled source, the generated voltage or current does not vary with the load to which it is connected; this implies a zero output impedance for a voltage source and an infinite output impedance for a current source. In practice, actual controlled sources have finite output impedance, which causes the generated source to vary somewhat with the load. Circuit representations of the four ideal controlled sources are given in Figure 14.1. The input terminals on the left represent the controlling voltage or current, and the output terminals on the right represent the controlled voltage or current; the value of the controlled source is proportional to the controlling input through the constants g, m, b, and r.
