General comments only:

0.01% of *setpoint* is approximately impossible  at the bottom end
(for values of approximately approaching unity).
Hmm 1 nanoamp. That's 1000 pA. Sounds like fun.

Delta Sigma converter with notional 24 bits seems a good starting
point given low conversion rate.

Digikey have good quantities of a number of different devices. They
appear to be obtainium ones.


      R
--=20
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