Can we measure currents of nano or pico amperes range reliably because I assume that normal lab multimeters won't work in this case because of their high internal resistances and noise. We get these low current values in simulation though but I couldn't figure out any method to measure such low current values using any instrument or any other method.
It depends on many factors, but generally such currents (e.g. a few pA from photodiode) can be measured.Sometimes even fA.
1. 'Cheap, quick and dirty': decent usual DMM multimeter has 10Mohm or so of input resistance in voltage mode. That means 1nA forced through it will be seen as 10mV.
2. Advanced specialized low current meters and electrometers like e.g. Keithley 6430 which has +-1pA at the lowest range:
https://www.newark.com/keithley/6430/source-meter-voltage-current-2w/dp/59T8598
3. You can assemble amplifier circuitry using electrometric opamp like
http://www.ti.com/product/LMC6001
and e.g. 10 Gohm feedback resistor.
Bhupendra Desai, Ambrish Devanshu and Nikolay Pavlov Thanku for ur responses!
One can also add:
4. https://www.femto.de/en/products/current-amplifiers/sub-femto-ampere-var-gain-ddpca.html
Neha:
Best regards. I am adding these papers if they are helpful. Please recommend my answer if these papers address your particular problems.
Sincerely,
Dr. Nabil Shovon Ashraf
Associate Professor
SAC 932
Department of ECE
North South University
Dhaka, Bangladesh.
Neha: If your research allows to spend money to buy a Keithley instrument, then I am attaching a model which you may purchase since the ammeter readings will of highest precision considering building supporting circuits and interfacing that might be required for using the generally used precision ammeters where the parasitics of the circuits may still produce error in the measurement. In that case direct instrument purchase may provide you the best solution. Please also look carefully the low level measurement handbook that I attached in earlier response.
Sincerely,
Dr. Nabil Shovon Ashraf
Associate Professor
SAC 932
Department of ECE
North South University
Dhaka, Bangladesh.
hi, i have used keithley instrument for thin film conductivity in order of nano amps. you can visit keithley website for the same.
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