ABSTRACT
The important signals for circuits include the step, impulse, ramp, sinusoid, and dc signals. These signals are widely used and are described in the time domain. Since the exponential factor only approaches zero as t increases without limit, such functions theoretically last forever. A mathematical model of an electric circuit contains ideal models of physical circuit elements. Numerous functional forms are useful in describing the source variation with time. The preceding ideal independent sources constrain the terminal voltage or current to a known function of time independent of the circuit that may be placed across its terminals. Ideal sourceAn ideal model of an actual source that assumes that the parameters of the source, such as its magnitude, are independent of other circuit variables. A controlled source may be controlled by more than one circuit variable, but we will discuss those having a single controlling variable since multiple controlling variables require no new ideas.
