08.02.2022
Top of the DART printed-circuit board (green) with connectors (light gray) and housing (dark gray). The measurement amplifier is provided with an additional shielding case (black), the cover of which has been removed for clarity. More components (e.g., analog/digital converter and reference voltage) are located at the bottom of the board.
Important milestones have been reached in the development of PTB's new noise thermometer, the Dual-mode Auto-calibrating Resistance Thermometer (DART). The patent, applied for in October 2020, was recently granted and will be published in a few months. After extensive investigation and optimization of the basic DART components with a Josephson Arbitrary Waveform Synthesizer (JAWS) in the past year, final calibration and circuit concepts were developed. Based on these concepts, a 15 cm x 5 cm circuit board with 800 components has now been designed, which contains all sensitive parts of the measurement electronics. As a result, all components affecting the measurement uncertainty (measurement amplifier with input multiplexer, filter, and analog/digital converter as well as reference voltage and bias current generation) are housed in a compact shielded enclosure. This enables a user-friendly measurement setup and allows reliable industrial production of the DART.
The next phase focuses on the development of the interface electronics for computer control of the sensitive measurement electronics via a measurement software yet to be developed. Both the power supply and the communication will be realized with galvanic isolation via a USB port of the measurement computer. Subsequently, extensive tests of a complete DART prototype and a final technology transfer are planned. This is intended to enable wide dissemination of the DART and establish its innovative technology in metrology.
Publication:
D. Drung and C. Krause, "Dual-mode auto-calibrating resistance thermometer: a novel approach with Johnson noise thermometry," Rev. Sci. Instrum. 92, 034901 (2021)
DOI: https://doi.org/10.1063/5.0035673
D. Drung, M. Kraus, and C. Krause, "Calibration of the dual-mode auto-calibrating resistance thermometer with few-parts-per-million uncertainty," Meas. Sci. Technol. 33, 015008 (2022)
DOI: https://doi.org/10.1088/1361-6501/ac2c48
Contact:
C. Krause, 7.6, E-Mail: 
Christian.Krause(at)ptb.de