High-Accuracy Current Amplifier for Small Electric Currents

A new instrument for the measurement and generation of small direct currents, the Advanced Laboratory Current Amplifier (ALCA), is presented. It is based on the concepts of the Ultrastable Low-noise Current Amplifier (ULCA) and aims for improved user-friendliness and cost-efficient fabrication while still achieving very low measurement uncertainties. Different ALCA variants are designed to cover current ranges between microamperes and sub-femtoamperes. The predicted parameters of two basic ALCA variants are evaluated and discussed. In addition, we show an initial long-term study of the uninterruptible power supply used.