Sun Dec 26 11:56:12 EST 2010

Weird brain fart: open vs. closed loop bode plots

Context: state variable filter.

If 2 integrators produce 180 degree phase shift, why does the circuit
oscillate where loop gain = 1, and not where gain is larger?

Very bad formulation and I don't know if I can fix that, but the idea
is this: don't confuse time domain behaviour with s-parameter model.
If the frequency is well below 1/tau the integrators are "fast enough"
and will follow the input signal.