The frequency response of a network is its steady-state response to sinusoidal excitation signal over a wide frequency range. From the sinusoidal analysis of circuits, it is known that the response of a linear circuit to a sinusoidal forcing function can be identified in terms of its magnitude and phase angle. Both these quantities, the ratio of the magnitude of response to the magnitude of excitation signal and the phase shift of response with reference to the excitation signal, are influenced by parameters of the network and the frequency of excitation signal. The interesting aspect of frequency response is that it is possible to estimate the dynamic time response of a network from its frequency response. Even though the exact time response can be obtained from the frequency response by using the inverse Fourier transform, this method is not used because of its complexity. On the other hand, the frequency response plot is used to obtain an estimate of the time response in terms of some equivalent damping ratio and natural frequency.
The popularity of the frequency-response method among engineers is due to several advantages of this method.
This chapter describes the various aspects of frequency response and shows how the frequency response of electrical circuits can be obtained. The importance of pole-zero plot is also highlighted.
Determination of frequency response of a circuit is essential for several applications. Some of these applications are listed below.
The list of sections in this chapter are shown below.