Fundamentals of Circuit Theory Approximation

This chapter explains principles that unify communication theory and circuit theory approximations. It next discusses classification of linear and nonlinear systems: time-invariant and time-variant systems, lumped-parameter and distributed-parameter systems, instantaneous (memoryless) and dynamic (with memory) systems and analog and digital systems. The chapter describes the significance of the complex frequency variable in the analysis of electrical circuits. It also describes some of the benefits of circuit theory. Circuit theory provides simple solutions to problems that would otherwise become hopelessly complicated if authors were to use electromagnetic field theory. Communication channel can be characterized by an exponential driving function, and that represents a major simplification in the analysis of communication systems. The chapter highlights the essential assumptions and the success of the frequency analysis approach that authors take for granted in analyzing electrical networks.