Realization of an Inductance Scale Traceable to the Quantum Hall Effect Using an Automated Synchronous Sampling System

In this paper, the realization of an inductance scale from 1~$\mu$H to 10~H for frequencies ranging between 50~Hz to 20~kHz is presented. The scale is realized directly from a series of resistance standards using a fully automated synchronous sampling system. A careful systematic characterization of the system shows that the lowest uncertainties, around 12~$\mu$H/H, are obtained for inductances in the range from 10~mH to 100~mH at frequencies in the kHz range. This new measurement system which was successfully evaluated during an international comparison, provides a primary realization of the henry, directly traceable to the quantum Hall effect. An additional key feature of this system is its versatility. In addition to resistance-inductance (R-L) comparison, any kind of impedances can be compared: R-R, R-C, L-L or C-C, giving this sampling system a great potential of use in many laboratories around the world

New proposed method for traceability dissemination of capacitance measurements

Capacitance measurements at the National Institute of Standards (NIS), Egypt, are traceable to the Bureau International des Poids et Mesures (BIPM). It calibrates the main NIS standard capacitors, AH11A. In this paper, traceability of the BIPM capacitance measurements could be used to evaluate a new accurate measurement method through an Ultra-Precision Capacitance Bridge. The new method is carefully described by introducing some necessary equations and a demonstrating chart. Verification of this new method has been realized by comparing its results for the 10 pF and 100 pF capacitance standards with the results obtained by the conventional substitution method at 1 kHz and 1.592 kHz. The relative differences between the two methods are about 0.3 µF/F, which reflect the accuracy of the new measurement method. For higher capacitance ranges, the new measurement method has been applied for the capacitance measurements up to 1 μF at 1 kHz. The relative differences between the two methods are in the range of 5.5 µF/F on the average which proves the acceptable accuracy and the reliability of the new method to be used

An international comparison of phase angle standards between the novel impedance bridges of CMI, INRIM and METAS

partially_open8We report here the results of a comparison of electrical impedance standards aimed at evaluating four novel digital impedance bridges developed by the national metrology institutes CMI, INRIM and METAS. This comparison, which is the first of its kind, involved phase angle impedance standards developed by TÜBITAK UME with phase angles of  ± 30° and  ± 60°, and magnitudes ranging from about 100 Ω to 1 MΩ. The comparison demonstrated agreement among the measurement results obtained with the different bridges, and allowed us to gather information on the stability of the phase standards and on more critical aspects related to the characterization of the bridges.partially_openOrtolano, Massimo; Palafox, Luis; Kučera, Jan; Callegaro, Luca; D’Elia, Vincenzo; Marzano, Martina; Overney, Frédéric; Gülmez, GülayOrtolano, Massimo; Palafox, Luis; Kučera, Jan; Callegaro, Luca; D’Elia, Vincenzo; Marzano, Martina; Overney, Frédéric; Gülmez, Güla

RF Transport Electromagnetic Properties of Graphene from DC to 110 MHz

The paper describes measurement of RF transport electromagnetic properties of CVD graphene over the DC to 110 MHz frequency range at room temperature. Graphene on Si/SiO2 substrate was mounted in a shielded four terminal-pair (4TP) adaptor which enabled direct connection to a calibrated precision impedance analyser for measurements. Good agreement is observed for the DC four-probe resistance and the 4TP resistance at 40 Hz, both yielding R ~104 Ohms. In general the apparent graphene channel electromagnetic properties are found to be strongly influenced by quantum contact effects, such as resistance and capacitance, particularly at DC and low frequencies f < 1 MHz. A phenomenological lumped-parameter equivalent circuit model is presented which matches the frequency response of the graphene 4TP impedance device over approximately seven decades of the frequency range of the applied transport alternating current. Based on this model, the intrinsic graphene channel resistance is found to be RG = 2.2 Ohms or sheet resistance of 3.85 Ohms/sq, which is frequency independent, with each contact impedance being RC = 51.6 Ohms and CC = 1.2 nF. These results suggest that our RF 4TP method may be more accurate and reliable than the conventional DC four-probe method for measuring the intrinsic sheet resistance of single-atom thick materials such as graphene. This may be significant for the production and optimisation of graphene for solar-cells and touch-screen displays where sheet resistance (combined with its optical transparency) figures-of-merit play an important role, particularly in comparison with the values of the current material of choice, indium tin oxide (ITO), for such applications

An Arduino microcontroller based RLC meter

An RLC meter is a single electronic instrument or device which is capable to measure the Resistance (R), Inductance (L) and Capacitance (C). This instrument has wide applications in electrical and electronics laboratory, industry and engineering research works. Nowadays, a large variety of RLC meter is available. The high precision RLC meter is slow responding, bulky size, higher operational power and expensive. However, many applications do not need very high accuracy measurement, for this reason, this paper has proposed a simple and moderate precision RLC meter based on Arduino microcontroller which would overcome the existing issues. The proposed design has been verified by simulation and experimentally. The results show good compliance with theory and experiment; in addition, it shows moderate accuracy

The ampere and the electrical units in the quantum era

By fixing two fundamental constants from quantum mechanics, the Planck constant $h$ and the elementary charge $e$, the revised Syst\`eme International (SI) of units endorses explicitly quantum mechanics. This evolution also highlights the importance of this theory which underpins the most accurate realization of the units. From 20 May 2019, the new definitions of the kilogram and of the ampere, based on fixed values of $h$ and $e$ respectively, will particularly impact the electrical metrology. The Josephson effect (JE) and the quantum Hall effect (QHE), used to maintain voltage and resistance standards with unprecedented reproducibility since 1990, will henceforth provide realizations of the volt and the ohm without the uncertainties inherited from the older electromechanical definitions. More broadly, the revised SI will sustain the exploitation of quantum effects to realize electrical units, to the benefit of end-users. Here, we review the state-of-the-art of these standards and discuss further applications and perspectives.Comment: 78 pages, 35 figure