[sdiy] OTA's, Iabc, and the magic of V to I

[Nils Pipenbrinck]

Maybe some of you remembers, I've started a thread rambling over OTA
currents and curves a week ago or so.

I've done some more measurements, and I have to admit, that Magnus is right.
The atanh curve I plottet was not caused by the shitty current source I've
used (a resistor to V+) but the overdriven differential amplifier.

For some reason I assumed, that I can drive the OTA input with 300mV without
going into the non-linear region. Well, I plotted some more curves with a
working current source, and now I won't go over 45mV Vdiff. Don't ask me
where I got these 300mV from. I also cross-checked with other circuits and
found out that the ASM-1 VCA is just driving it with ca. 1mV. Maybe I'm even
to optimistic with my 45mV. At least my next design will not distort that
badly, and if it does I know how to fix it.

I still don't understand how the guts of the OTA's work, but that's not that
important for me. I know how to practially use and design around them. Just
wondering what will be the next thing I stumble into.. Gee, maybe I should
start and write a website around these OTA ramblings. They are so easy to
use once you've understood how to use them.


A friendly and peacefull Xmas for all,

	Nils Pipenbrinck