Design and Verification of a New Current Source for Tsinghua Tabletop Kibble Balance

TL;DR

This paper introduces a highly stable, cost-effective current source for Tsinghua Kibble balances, achieving tenfold faster measurement stability through a novel composite control topology and digital feedback.

Contribution

A new composite 'coarse-fine' control topology with dual-DAC and digital feedback for ultra-stable current sources in precision mass measurements.

Findings

Allan deviation reaches 1 nA/A at 3-minute integration

Tenfold improvement in measurement speed over commercial sources

Cost-effective design suitable for high-precision mass realization

Abstract

This paper presents an ultra-stable current source tailored for the one-mode, two-phase (OMTP) measurement scheme in Tsinghua tabletop Kibble balances. To achieve simultaneous high resolution and nA/A-level stability, a composite 'coarse-fine' control topology is proposed, utilizing a dual-DAC architecture and an active digital feedback loop. Experimental results show that the Allan deviation reaches 1 nA/A at an integration time of approximately 3 minutes, representing a tenfold improvement in measurement speed compared to commercial-source-based setups. Furthermore, the design offers a significant cost advantage, providing a satisfying option for high-precision, cost-effective mass realization.