Question

1. Discus the differences between a passive and an active filter.

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Answer 1

an active filter has a gain which is in our control. while a passive filter has a fixed gain. this means, indirectly, that i can also change my frequency response of the filter after suitably designing the circuit, while in passive filter case, that is not possible.

application wise, active filters are made adaptive, to cater for statistical changes in the signal. e.g. minimum variance filter for adaptive nulling in direction-of-arrival estimation. while passive filters are used for fixed scenarios e.g. bandpass filter at the output of IF stage.

the amplifiers in active filters can either be voltage or operational so as to stabilize the filter's behavior. This amplitude response can be modeled by an ideal frequency response curve. , active filters utilize no inductors but are easier to design than passive filters. The five basic types of active filters are low pass (which reduces frequencies below the cutoff), high pass (which increases frequencies above the cutoff), band pass (which shifts frequencies above and below the cutoff), band reject (which reduces some frequencies and allows others) and universal (which allow the user to make the filter function as any of the other four types). Passive filters have similar basic types, but the output level is always lower than the input level. Some disadvantages of active filters include the requirement of a power supply to function unlike passive filters. shows how active filters can produce high gains, but passive filter DO NOT