Synthesis of precision AC waveforms using a SINIS Josephson junction array
ABSTRACT A synthesizer of precision AC waveforms based on a SINIS Josephson junction array has been developed. The array is divided into 15 segments in a binary series and the segments are individually biased using a high speed bias source with a 100 ns rise time. The design considerations and accuracy limitations of the system are discussed and comparisons between the synthesizer and thermal converters are presented.
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ABSTRACT: This paper deals with a new theoretical approach using micro- and nano-electromechanical systems to build alternating current (ac) voltage standards. The principle is based on the quadratic variation of the capacitance due to the displacement of at least one of the micro-machined electrodes as a result of an applied electrostatic force. In these systems the voltage reference presents a plateau according to the ac driving current, which makes it possible to define an ideal current-independent ac voltage standard as in dc voltage metrology using Zener diodes. This new approach allows us to define a voltage reference given by the value of the voltage plateau instead of just a single operating point in the well-known pull-in effect approach, in which the variation of the capacitance with the displacement is hyperbolic. Moreover, the working frequency range in this new approach is wider and is no longer limited by the mechanical resonance frequency of the system. Two microsystem architectures are proposed to realize such devices: the first one is based on electrodes in the shape of a triangle and the second one uses split finger electrodes with unequal lengths.Metrologia 01/2011; 48(1):40. · 1.65 Impact Factor
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ABSTRACT: Based on superconductor-insulator-normal metal-insulator-superconductor (SINIS) Josephson junction arrays (JJA), an ac Josephson voltage synthesizer has been successfully developed in National Institute of Metrology (NIM), China. The root mean square (rms) value of generated ac voltage is up to 0.84 V. The frequency of synthesized voltage is up to 200 Hz and the uncertainty of synthesized voltage at 60 Hz is less than 5 parts in 106. This Josephson ac waveform synthesizer mainly relies on a domestic high speed bias source which synthesizes the waveform by prompt switching of bias current for a programmable Josephson array.01/2010;
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ABSTRACT: The advent of the fundamental constants RK (the von Klitzing constant) and KJ (the Josephson constant) in electrical metrology and the growing development of nanotechnologies have totally changed the vision and the practice of the National Metrology Institutes (NMIs), opening a modern era of metrology and arousing a growing interest in a possible re-definition of the international system of units (SI). The Josephson effect (JE) and the Quantum Hall effect (QHE), at the origin of these fundamental constants, constitute the keystone of a new approach to electrical units, when one considers the very high level of reproducibility of these units, never seen before. On the other hand, the Watt balance experiment in which these constants play a part could be the origin of a new SI definition, replacing the mass unit ‘the kilogram’ as a fundamental unit by the Planck constant h. It thus seems that the implementation of experiments aimed at demonstrating the coherency between the theoretical and phenomenological values of these constants is a major objective. In this framework the metrological triangle experiment associating QHE, JE and single electron tunnelling effect would play a major role in checking the consistency of these fundamental constants in terms of the Planck and electron charge constants. This article gives briefly an outline of these quantum phenomena and their metrological applications in NMIs for the realisation of electrical units and the determination of the fundamental constants. To cite this article: F. Piquemal et al., C. R. Physique 5 (2004).Comptes Rendus Physique 10/2004; 5(8):857-879. · 1.64 Impact Factor