Sallen-Key Band-Pass Filter

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Sallen–Key topology filters are second-order active filters whose simplicity makes them a popular choice for general filtering applications. In this Demonstration, Bode plots are produced for single-stage low-pass and high-pass filters or a combination of these filters, up to 10 stages each.

Contributed by: Jeremiah Woods (May 2012)
Open content licensed under CC BY-NC-SA



The transfer function, cutoff frequency, and for low-pass and high-pass filters (with non-unity gain) are

1. ;

2. ;

3. ;

4. ;

5. ;

where and , , , , , are the resistances and capacitances.

For higher-order filters, the transfer funtions 1 and 2 are raised to the order of the filter. For a high-pass (low-pass) filter, set the order of the low-pass (high-pass) filter to "0".


[1] "Analysis of the Sallen–Key Architecture." Texas Instruments. (Sep 2002)

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