原创 Designing an multiple feedback bandpass filter

The major component of many circuits in Audio/Video application is a multiple feedback bandpass filter (MFB filter). Below is the circuit

The major advantages for this filter are its simplicity and the high quality factor; which can go up to 10. Note the frequency response for a center frequency of 250 Hz. Look how sharp the peak is at 250 Hz which means that the quality of the filter is high.

Now let’s sweep the resistor R4 from, say, 1 kΩ to 50 kΩ. Now see what happens to the response.

You can see that the gain of the response increases as the resistance of R4 is increased. Like this you can vary the amplitude of a certain frequency using this filter – in this case which is 250 Hz.

Multiple Feedback Bandpass Filter:

http://www.docircuits.com/circuit-editor/117