I have a bandpass filter as follows:

But I would like calculate the low pass corner frequency which I am stuck at right now.

The transfer function I got for the low pass sallen-key is

2484375/(s^2 + 1762.5 + 1562500)

after normalizing the nominator and last term of the denominator to "1", I found that it is not an Butterworth filter design.

I would like to seek your advice to find out the LP corner frequency.

Thanks!

your equation looks wrong. do you mean 2484375/(s^2 + 1762.5

**s** + 1562500)

Posted on: May 01, 2016, 06:41:25 06:41 - Automerged

I have a bandpass filter as follows:

But I would like calculate the low pass corner frequency which I am stuck at right now.

The transfer function I got for the low pass sallen-key is

2484375/(s^2 + 1762.5 + 1562500)

after normalizing the nominator and last term of the denominator to "1", I found that it is not an Butterworth filter design.

I would like to seek your advice to find out the LP corner frequency.

Thanks!

This is what I came up with from you numbers:

numerator = pi/2 * 1562500

sqrt(1562500) = 1250 = omega^2

fc = 200Hz

alpha = 442 for Q = 1/sqrt(2) for a butterworth

alpha = 881 your alpha

where sallen key equation =