Equivalent circuit

Article By:

Huelsman, Lawrence P. Department of Electrical and Computer Engineering, College of Engineering and Mines, The University of Arizona, Tucson, Arizona.

Last reviewed:January 2020

DOI:https://doi.org/10.1036/1097-8542.240100

A representation of an actual electric circuit or electronic device by a simple circuit whose behavior is very near to that of the actual circuit over a specified range of conditions. When these conditions are satisfied, the equivalent circuit may be said to constitute a macromodel of the actual circuit. The use of equivalent circuits is important in many of the analysis and design operations associated with electronic circuits. For example, a frequently used electronic device is the operational amplifier. One of the better-known operational amplifiers, the μA 741, is realized as an integrated circuit containing over 20 transistors. Many electric circuits, for example, active-RC (resistance-capacitance) filters, require the use of large numbers of operational amplifiers. In such applications, the use of equivalent circuits greatly simplifies analysis and design operations. See also: Electric filter; Integrated circuits; Operational amplifier; Transistor

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