Low Current Sensing Technique

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Hello Everyone,
I am looking for a method of low current sensing. I need to measure the leakage current of Mosfet but i am not able to find any sensor or module to measure current in nano amps. Can anyone guide me on this?
 

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Hi,

I guess low voltage DC. Please confirm.

If so then a resistor to convert current to voltage is a valid method.
Maybe combined with an Opamp. Look for "TIA circuit".
Please define voltage, current_range, expected accuracy and resolution.

Klaus
 

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You can find benchtop picoammeters in most major
test instrument mfrs' product lines although they are
a niche function.

You could build your own with an op amp and
precision resistor, transimpedance style and use
a generic DMM on the output voltage. Need to
get a good CMOS or JFET input op amp for high
Zin, and perhaps some care with PCB design.

A really crude option is a precharged capacitor
and timer, I=C*dV/dt. Take an open socket reading
to get at any fixture current which would be
superimposed. You could use a 'scope probe
(although its 10Mohms will perhaps dwarf the
leakage current of interest) to get the time for
dV=1V, or whatever.
 

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