A measurement setup to calibrate picoammeters in dc current in the range 100 pA ÷100 nA

This paper describes a measurement setup for the calibration of pico-ammeters in dc current in the range 100 pA divide 100 nA. The system is based on a 100 MOmega Hamon network developed at INRIM to improve the traceability level of the maintained 1 GOmega standard. Besides the Hamon network, the measurement system consists of a precision dc voltage source and an electronic circuit used as voltage guard driver. A comparison with a different technique and an uncertainties considerations for the system and are also reported.