picoammeter

[hamisu]

I have a project that incorporates the measurement of very low currrent in the range of nano-amps. Could any one please assist with a suitable circuit diagram that will be capable of measuring such a quantity with precision? I mean a circuit diagram, not a device

 

[Optikon]

I have a project that incorporates the measurement of very low currrent in the range of nano-amps. Could any one please assist with a suitable circuit diagram that will be capable of measuring such a quantity with precision? I mean a circuit diagram, not a device

You can use an opamp such as LMC662 and make an I to V converter with a 1G-OHM resistor.

See this:
**broken link removed**

I'm not going to spend time drawing a diagram for you but they exist on the web and in the datasheet already. Use them.

Follow all the guidelines about guarding and air wiring if you want the most precision low current measurements. There will be resistor tolerances and offsets that will degrade your precision but those can be calibrated out.