One Key
Sallen Key Filters – Why is there a bootstrap between one of the elements and output?
In an active Sallen-Key low pass filter, one of the caps is bootstrapped to the output. Do any one know why?
It’s not a bootstrap, it’s a feedback path. And the reason that it’s there is to put a pole in the transfer function at some desired frequency. The other pole is placed by the other capacitor (to ground) at the input summing junction.
You *do* understand about feedback loops, complex frequency, and transfer functions…… Don’t you?
Doug
