Since active devices usually supply signal energy to an electronic circuit, and since energy can only be transformed and not created, a source of energy is needed when active devices are present. This energy is usually obtained from batteries or through rectification of sinusoidal voltages supplied by power companies. When inserted into an electronic circuit, such a source of energy fixes the quiescent operation of the circuit; that is, it allows the circuit to be biased to a given operating point with no signal applied, so that when a signal is present it will be processed properly. To be useful, an electronic circuit produces one or more outputs; often inputs are applied to produce the outputs. These inputs and outputs are called the signals and, consequently, generally differ from the bias quantities, though often it is hard to separate signal and bias variables. Biasing of electronic circuits is an important, non- trivial, and often overlooked aspect of their operation.
A plan, sketch, drawing, chart or graph, not necessarily representational, that explains, demonstrates or clarifies the arrangement and relationship of the parts to a whole.
A general term referring to a system or part of a system of conducting parts and their interconnections through which an electric current is intended to flow. A circuit is made up of active and passive elements or parts and their interconnecting conducting paths.
Electric circuit theory includes the study of all aspects of electric circuits, including analysis, design, and application. In electric circuit theory the fundamental quantities are the potential differences (voltages) in volts between various points, the electric currents in amperes flowing in the several paths, and the parameters in ohms or mhos which describe the passive elements. Other important circuit quantities such as power, energy, and time constants may be calculated from the fundamental variables. For a discussion of these parameters.