ABSTRACT
Filters are important-if not indispensable-tools for electronic engineers. Almost every electronic system has at least one fi lter. A good example is the simple RC fi lter found in the DC power supply of any electronic system. This simple circuit plays a major role in determining the quality of the system. It reduces the amplitudes of the undesired fl uctuations (usually called ripples) resulting from the imperfect rectifi cation of the AC (sinusoidal) supply voltage. Such ripples are harmonics of the supply frequency; that is, they are audible. Power supplies of high-fi delity systems should therefore be well fi ltered to minimize such a disturbing effect, as it greatly affects the output of the system. In some sensitive devices that deal with voltages of very low amplitudes, such as EKGs and EEGs, interferences from the supply frequency may distort the waveform to the extent that the diagnosis is affected. Therefore, a fi lter is designed and included to highly attenuate the supply frequency component. Filters are used extensively in many fi elds, including communications, signal processing, biomedical, telemetry, control applications, and others.
