Improved Calibration of Instruments for Small Direct Currents

TL;DR

This paper introduces a new calibration method using the Ultrastable Low-noise Current Amplifier (ULCA) for small direct currents, achieving lower uncertainties and simplifying the calibration process for picoammeters and low-current sources.

Contribution

The paper presents the ULCA as a novel, unified calibration tool for small currents, improving accuracy and ease over existing methods.

Findings

ULCA achieves lower calibration uncertainties.

ULCA simplifies calibration procedures.

Calibration range covers 1 fA to 1 μA.

Abstract

We report on new calibration methods for picoammeters and low-current sources. The "Ultrastable Low-noise Current Amplifier" (ULCA) was used for the exemplary calibration of commercial state-of-the-art ammeter and current source instruments in the current range between 1 femtoampere and 1 microampere. The uncertainties achieved are compared with results obtained from two other calibration methods for small direct currents. It is shown that using the ULCA as calibrator allows achieving lower uncertainties together with the benefit of easier handling compared to alternative techniques. Also, the ULCA allows performing current meter and source calibrations between 1 femtoampere and 1 microampere with a single method.