[sdiy] Instability in an OTA-C LP cell

[Olivier Gillet]

I spent some more time playing with this and trying to find how the
resistor made a difference... It was hard to capture on the scope, but
adding the 47k seemed to act as a slew limiter (or low-pass) on the
sharp edges of the input - quite noticeable on a square wave input.

In the end, I went with this solution which doesn't rely on ugly
side-effects and which I have not managed to crash (yet):
http://dl.dropbox.com/u/612135/ota_op_amp_integrator.png

Olivier