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Active filter
Analog circuit which filters an electronic signal using an amplifier / From Wikipedia, the free encyclopedia
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An active filter is a type of analog circuit implementing an electronic filter using active components, typically an amplifier. Amplifiers included in a filter design can be used to improve the cost, performance and predictability of a filter.[1]
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An amplifier prevents the load impedance of the following stage from affecting the characteristics of the filter. An active filter can have complex poles and zeros without using a bulky or expensive inductor. The shape of the response, the Q (quality factor), and the tuned frequency can often be set with inexpensive variable resistors.[2] In some active filter circuits, one parameter can be adjusted without affecting the others.[1]