Very low current measurement. How to?

[Ludo3.14]

Dear all,

I'm trying to develop a miniaturized picoammeter to measure very low current (in the order of nA) to be analyzed and transmitted.
Keithley 6485/6487 are way too big for my purpose.
Do you suggest any particular hardware (opamps) that are both small and effective?

Thank you in advance!

[Kleinstein]

The circuit of choice is usually a transimpedance amplifier with an CMOS OP. Suitable OP's could be LMC6001, LMC6041, LMC6062 and similar.  A few nAs is not even that low - so even simple CMOS types like MCP6001 , TLC271 might be good enough.

[uncle_bob]

Hi

Is the current ground referenced or is it running between two nodes that need to be isolated?

Is there already power associated with those nodes (if they are floating)?

Lots of possibilities ....

Bob

[danadak]

Bob Pease discussion on this -

http://electronicdesign.com/test-amp-measurement/whats-all-femtoampere-stuff-anyhow


What's All This Teflon Stuff, Anyhow?
http://electronicdesign.com/test-amp-me ... uff-anyhow


What's All This Femtoampere Stuff, Anyhow?
http://electronicdesign.com/test-amp-me ... uff-anyhow





Regards, Dana.