Comparison between two dc low current traceability chains

We report on a comparison experiment between a low dc current source based on the capacitance-voltage method, and an ultrastable-low noise current amplifier (ULCA). The two instruments can be calibrated independently using different methods and traceability paths. The agreement is of a few parts in 10 ⁵ for currents close to 10 pA and 100 pA; the residual deviation might be related to the frequency dependence of the capacitance employed in the source.