Active filter

[Silves]

I have a general question. What is the advantage of using active filters? Are they betetr than the simple filter with capacitors and resistors and coils?

[Silves]

No one?

[Supernova]

This question also bothers me... 

[kam]

An active filter is a type of analog electronic filter, distinguished by the use of one or more active components i.e. voltage amplifiers or buffer amplifiers. Typically this will be a vacuum tube, transistor or operational amplifier.

Active filters have two main advantages over passive filters. The first is that the amplifier powering the filter can be used to shape the filter's response, e.g., how quickly and how steeply it moves from its passband into its stopband. (To do this passively, one must use inductors, which tend to pick up surrounding electromagnetic signals and are often quite physically large.) The second is that the amplifier powering the filter can be used to buffer the filter from the electronic components it drives. This is often necessary so that they do not affect the filter's actions.

[blackrosejay0918]

I agree to the second , that the amplifier powering the filter can be used to buffer the filter from the electronic components it drives.


_________________
Humidifier filters

[kam]

I agree to the second , that the amplifier powering the filter can be used to buffer the filter from the electronic components it drives.


_________________
Humidifier filters

Don't they have faster response?

[circuitfella11]

both have advantages over the other. passive filters can handle big voltages and currents, less components to use in filtering, noise is due to the resistors and no bandwidth limit. While active filters have high input impedance, easier to tune and small in size.

sometimes we choose according to some specs: frequency, bandwidth, power requirement, gains etc.

hope this helps.