Calibration of low-current meters at nA level with the capacitance-charging method

The most accurate generation of dc currents in the lower ranges is performed with the capacitance-charging technique. Implementations of the method are typically limited to an upper current in the 100 pA range. Here we present a range extender which can be employed as plug-in in existing setups. The extender permits to scale the current of a ×10 factor and reach the nA range. Results of calibration of low-current meters with and without the use of the extender are reported