You're right! What a silly error!I think your C2 is in the wrong spot.
https://en.wikipedia.org/wiki/Sallen–Key_topology#Application:_low-pass_filter
Shouldn't it be closer to 1/2πRC?
- the cut off frequency should be 1/RC= 333 Hz while from simulation seems to be lower. Why?
The response raises at higher frequencies where the high frequency gain of the op amp is not sufficient to provide proper feedback and the signal goes directly to the output through C1.
- at high frequency the response raises. why?
Check out reference #3 in the Wikipedia article provided by @shteii01.why at high frequency the response raises. Can you explain me this?
Not sure.Reading here and there, I've found the sentence "At the frequency where the amplifier’s output impedance is greater than the impedance of the resistor (R1), the feedback looks inductive and the response increases at a rate of 20 dB/decade."
What does it mean "looks inductive"? How is it possible?