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3 Time-Dependent Circuit Analysis

3.1 Sinusoidal Steady-State Phasor Analysis

3.2 Transients in Circuits

3.3 Laplace Transform

3.4 Frequency Response

3.5 Computer-Aided Circuit Simulation for Transient Analysis, ac Analysis, and Frequency

Response Using PSpice and PROBE

3.6 Use of MATLAB in Computer-Aided Circuit Simulation

3.7 Learning Objectives

3.8 Practical Application: A Case Study—Automotive Ignition System

Problems

The response of networks to time-varying sources is considered in this chapter. The special

case of sinusoidal signals is of particular importance, because the low-frequency signals (i.e.,

currents and voltages) that appear in electric power systems as well as the high-frequency signals

in communications are usually sinusoidal. The powerful technique known asphasor analysis,

which involves the use of complex numbers, is one of the electrical engineer’s most important

tools developed to solve steady-state ac circuit problems. Since a periodic signal can be expressed

as a sum of sinusoids through aFourier series, and superposition applies to linear systems, phasor

analysis will be used to determine the steady-state response of any linear system excited by a

periodic signal. Thus the superposition principle allows the phasor technique to be extended to

determine the system response of a linear system. Thesinusoidal steady-state response of linear

circuitsis presented in Section 3.1. The response when the excitation is suddenly applied or

suddenly changed is examined next in Section 3.2. The total response of a system containing

energy-storage elements (capacitors and inductors) is analyzed in terms of natural and forced

responses (or transient and steady-state responses). TheLaplace transformation,which provides

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