Xpander VCF

[jh.]

> Open loop transfer function and stability criteria a la Bode?

Or whatever it is called. Phase margin, one dominant pole ...
I'd say the capacitor must be big enough that even with the
highest bias current (highest cutoff frequency for the other
stages) the "disabled" stage's pole formed by the external cap
and the bias current must still dominate over all the other parasitic
poles.

JH.