So higher Q doesn't mean less stability? Then why when I play with values the calculator says that the circuit will oscillate when Q goes higher than 0.5:
I tried these values:
R1 = 3k
R2 = 15k
R3 = 75k
C1 = 1uF
C2 = 20nF
Oscillation frequency
f = 6.6261486736273[Hz]
and if I rise C2 to 47nF I get Q = 0.33 and "The system does not oscillate."
No, I didn't simulate that yet to test if it's true.
I also tried with gain = 1. Still the same results.
Can you explain the impact of Q and what value should I try to achieve? I also noticed that if Q gets too high I get overshoot close to the cut-off frequency.
I don't know what you're talking about, but a Q factor of 0.5 is very low.
Once again, you seem to mix up the Q with the damping ratio ΞΆ.
I don't really know what they mean by oscillation on this website.
It looks like they mean the frequency were the "boost" is of the Q.
You should read a bit more on to it like;
https://www.maximintegrated.com/en/app-notes/index.mvp/id/1762https://www.edn.com/electronics-blogs/bakers-best/4418766/Closer-to-real-world-analog-filtersThere are many more examples and explanations.
In general for Sallen Key filters you're totally fine for Q factors up to 3-5.
For most practical circuits I wouldn't know why someone would even want to go higher than that.
One huge advantage is that the unity gain is much more accurate for example for example.
But in general all these advantages and disadvantages are only gonna be an issue when looking for the limits (high bandwith, high Q factor, huge gains)
So it's not really worth going all into crazy debates about it.