5 - Nonlinear Circuits

Abstract

This chapter deals with the explanation of nonlinear circuits. Circuit nonlinearity is often a desirable design feature. Many electronic circuits are designed to employ the nonlinear behavior of their components. The nonlinearity of the circuits' elements is exploited to provide functionality that could not be achieved with linear circuit elements. A nonlinear circuit or a network (a circuit with a relatively large number of components) consists of at least one nonlinear element, not counting the voltage and current independent sources. A circuit element is called nonlinear if its constitutive relationship between its voltage (established across) and it's current (flowing through) is a nonlinear function or a non-linear relation. Analysis of nonlinear circuits is more difficult than the analysis of linear circuits. Various tools are used to understand and capture nonlinear circuit behavior. Some approaches employ quantitative (numerical) techniques and the use of circuit simulators for finding the distribution of a circuit's currents and voltages for a variety of waveforms supplied by sources. Other tools employ qualitative analyses methods, such as those dealing with the theory for establishing the number of dc operating points a circuit may possess or dealing with the analysis of stability of a circuit's operating point. This chapter describes models of physical circuit elements and voltage and currents in nonlinear circuits.