Electrometer calibration with sub-part-per-million uncertainty

TL;DR

This paper demonstrates highly precise calibration of picoammeters using the ULCA, establishing a reliable standard for small-current measurements with sub-part-per-million uncertainty and discussing implications for calibration accuracy.

Contribution

It introduces a calibration method using ULCA for picoammeters, providing detailed device characterization and an advanced setup for transimpedance amplifier calibration.

Findings

ULCA provides stable, accurate calibration for picoammeters.

Calibration results confirm ULCA's suitability as a small-current standard.

Accuracy limits are discussed for picoampere-range measurements.

Abstract

We performed calibrations of four different commercial picoammeters using the Ultrastable Low-noise Current Amplifier (ULCA) as a calibrator current source operated in the range between 1 femtoampere and 1 microampere. The results allow the comprehensive characterization of the devices under test regarding noise, settling and burden voltage behavior as well as stability of the gain factor, and confirm the performance of the ULCA for use as small-current calibrator standard. Also, we present a further advanced setup for the calibration of transimpedance amplifiers. Accuracy limits for best electrometer calibrations in the current range between 1 femtoampere and 1 microampere and possible implications on corresponding calibration and measurement capabilities are discussed.