Fri May 23 11:47:52 EDT 2014

Sallen Key

I've always been intrigued by the Sallen-Key[1] (SK) topology.  One of
those strange bootstrappy circuits.  After learning the Korg filter is
a SK with resistors replaced by diodes / reverse transistors[2] I've
been even more intrigued.

Who comes up with that stuff?  At first glance it seems
counter-intuitive, so I'm more interested in how one would invent such
a circuit than to just calculate the transfer function, which is

[1] http://en.wikipedia.org/wiki/Sallen%E2%80%93Key_topology
[2] http://www.timstinchcombe.co.uk/index.php?pge=korg