The study of electronic circuits, signals, and systems is based on a
variety of models, each devised to facilitate the application of mathematical
methods to engineering problems. The laws of physics provide
basic models of charge motion, in terms of which we explain the observed
terminal behavior of elementary components and devices, such as
resistors, inductors, capacitors, diodes, transistors, and vacuum tubes.
From physical models and observed terminal characteristics, we make
circuit models that lead to simple circuits capable of performing basic
Operations or functions. These operations, such as amplification, addition,
multiplication, and time delay, serve as the elementary building
blocks or models with which we can construct models of more general
systems. By a system, we mean a model of a signal transmission or
processing operation, usually an interconnection of elementary models
performing basic operations.
In this volume we present methods suitable for handling more general
circuits, with more general signals applied. These methods form an
introduction to system theory.