> >I haven't used OTAs. I've built it with THAT2180 VCAs, to get rid of the > >offset issues of OTAs. > > I'm not familiar with that chip. Isn't it still a transconductance > amp? Any idea how good the offset vs Iabc is? It's a Blackmer cell. No offset to speak of (compared to OTAs), but needs a servo configuration which probably limits its speed. JH.