Re: Detecting currents less than one femtoamp?
From: Winfield Hill (Winfield_member_at_newsguy.com)
Date: 10/10/04
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Date: 10 Oct 2004 06:55:45 -0700
Boris Mohar wrote...
>
> He said LESS than 1fA. 10^-16 is 100 attoamperes
>
> It is doable with discrete front end of I/V op amp
> configuration. I used 3N155.
Tell us about your observed current offset and drifts.
(The 3n155 p-channel MOSFET is spec'd at 10pA maximum
gate leakage, for Vgs = -25V forward, admittedly a
rather silly and basically useless spec.)
Also, did you use any input protection circuitry?
What was the size of your feedback/sense resistor?
Where did you get it?
--
Thanks,
- Win
(email: use hill_at_rowland-dotties-org for now)
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