5,808 research outputs found
Realization of the farad from the dc quantum Hall effect with digitally-assisted impedance bridges
A new traceability chain for the derivation of the farad from dc quantum Hall
effect has been implemented at INRIM. Main components of the chain are two new
coaxial transformer bridges: a resistance ratio bridge, and a quadrature
bridge, both operating at 1541 Hz. The bridges are energized and controlled
with a polyphase direct-digital-synthesizer, which permits to achieve both main
and auxiliary equilibria in an automated way; the bridges and do not include
any variable inductive divider or variable impedance box. The relative
uncertainty in the realization of the farad, at the level of 1000 pF, is
estimated to be 64E-9. A first verification of the realization is given by a
comparison with the maintained national capacitance standard, where an
agreement between measurements within their relative combined uncertainty of
420E-9 is obtained.Comment: 15 pages, 11 figures, 3 table
A three-arm current comparator bridge, for impedance comparisons over the complex plane
We present here the concept of three-arm current comparator impedance bridge,
which allows comparisons among three unlike impedances. Its purpose is the
calibration of impedances having arbitrary phase angles, against calibrated
nearly-pure impedances. An analysis of the bridge optimal setting and proper
operation is presented. To test the concept, a two terminal-pair
digitally-assisted bridge has been realized; measurements of an air-core
inductor and of an RC network versus decade resistance and capacitance
standards, at kHz frequency, have been performed. The bridge measurements are
compatible with previous knowledge of the standards' values with relative
deviations in the 10^-5 -- 10^-6 range
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~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~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
An international comparison of phase angle standards between the novel impedance bridges of CMI, INRIM and METAS
We 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 TĂBITAK UME with phase angles ofââ± 30° andââ± 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
A Three-Arm Current Comparator Bridge for Impedance Comparisons Over the Complex Plane
We present here the concept of three-arm current comparator impedance bridge, which allows one to perform comparisons among three unlike impedances. Its purpose is the calibration of impedances having arbitrary phase angles against calibrated nearly pure impedances. An analysis of the bridge optimal setting and proper operation is presented. To test the concept, a two-terminal-pair digitally assisted bridge has been realized; preliminary measurements of an air-core inductor and of an RC network versus decadic resistance and capacitance standards, at kilohertz frequency, have been performed. The bridge measurements are compatible with previous knowledge of the standard values with relative deviations of parts in 10^{-5}
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 TĂBITAK UME with phase angles ofââ± 30° andââ± 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; KuÄera, Jan; Callegaro, Luca; DâElia, Vincenzo; Marzano, Martina; Overney, FrĂ©dĂ©ric; GĂŒlmez, GĂŒlayOrtolano, Massimo; Palafox, Luis; KuÄera, Jan; Callegaro, Luca; DâElia, Vincenzo; Marzano, Martina; Overney, FrĂ©dĂ©ric; GĂŒlmez, GĂŒla
A Comprehensive Analysis of Error Sources in Electronic Fully Digital Impedance Bridges
open12sĂŹFully digital impedance bridges are emerging as measuring instruments for primary electrical impedance metrology and the realization of impedance units and scales. This article presents a comprehensive analysis of electronic fully digital impedance bridges for both generating (based on digital-to-analog converters) and digitizing (based on analog-to-digital converters) bridges. The sources of measurement error are analyzed in detail and expressed by explicit mathematical formulas ready to be applied to the specific bridge and measurement case of interest. The same can be employed also as a basis to optimize the design and the operating parameters of digital bridges and evaluate the measurement uncertainty. A practical application of the analysis to the digital bridges developed and measurements performed in the framework of an international research project is presented.openOrtolano, Massimo; Marzano, Martina; D'Elia, Vincenzo; Mai Tran, Ngoc Thanh; Rybski, Ryszard; Kaczmarek, Janusz; Koziol, Miroslaw; Musiol, Krzysztof; Christensen, Andreas Elmholdt; Callegaro, Luca; Kucera, Jan; Power, OliverOrtolano, Massimo; Marzano, Martina; D'Elia, Vincenzo; Mai Tran, Ngoc Thanh; Rybski, Ryszard; Kaczmarek, Janusz; Koziol, Miroslaw; Musiol, Krzysztof; Christensen, Andreas Elmholdt; Callegaro, Luca; Kucera, Jan; Power, Olive
A fully digital bridge towards the realization of the farad from the quantum Hall effect
This paper presents the implementation of an electronic fully-digital impedance bridge
optimized for RC comparisons with equal impedance magnitudes, together with an evaluation
of the uncertainty. This bridge has been designed with the goal of realizing the farad directly
from the quantum Hall effect with a bridge uncertainty component at the 1E-7 level. Thanks to
its simple design, ease of operation and affordability, this bridge is suitable to be industrially
manufactured. Together with the increasing availability of graphene quantum Hall resistance
standards, this can provide an affordable quantum realization of the unit farad for metrology
institutes and calibration centres.
In this paper we present the uncertainty budget of an example measurement and the results of
the validation of the bridge against a suitably modified version of the traceability chain of the
Italian national standard of capacitance. The combined uncertainty of the bridge resulted from
repeated measurements (overall measurement time of about 200 min) is 9.2 Ă 10^â8, suitable for
the primary realization of the unit of capacitance from a quantized Hall resistance standard. The
crosstalk among the channels of the electrical generator is the most significant uncertainty
component, possibly reducible with internal shielding and filtering of the electronic generator
Quantifying device degradation in live power converters using SSTDR assisted impedance Matrix
pre-printA noninterfering measurement technique designed around spread spectrum time domain reflectometry (SSTDR) has been proposed in this paper to identify the level of aging associated with power semiconductor switches inside a live converter circuit. Power MOSFETs are one of the most age-sensitive components in power converter circuits, and this paper demonstrates how SSTDR can be used to determine the characteristic degradation of the switching MOSFETs used in various power converters. An SSTDR technique was applied to determine the aging in power MOSFETs, while they remained energized in live circuits. In addition, SSTDR was applied to various test nodes of an H-bridge ac-ac converter, and multiple impedance matrices were created based on the measured reflections. An error minimization technique has been developed to locate and determine the origin and amount of aging in this circuit, and this technique provides key information about the level of aging associated to the components of interest. By conducting component level failure analysis, the overall reliability of an H-bridge ac-ac converter has been derived and incorporated in this paper
Acousto-optic and opto-acoustic modulation in piezo-optomechanical circuits
Acoustic wave devices provide a promising chip-scale platform for efficiently
coupling radio frequency (RF) and optical fields. Here, we use an integrated
piezo-optomechanical circuit platform that exploits both the piezoelectric and
photoelastic coupling mechanisms to link 2.4 GHz RF waves to 194 THz (1550 nm)
optical waves, through coupling to propagating and localized 2.4 GHz acoustic
waves. We demonstrate acousto-optic modulation, resonant in both the optical
and mechanical domains, in which waveforms encoded on the RF carrier are mapped
to the optical field. We also show opto-acoustic modulation, in which the
application of optical pulses gates the transmission of propagating acoustic
waves. The time-domain characteristics of this system under both pulsed RF and
pulsed optical excitation are considered in the context of the different
physical pathways involved in driving the acoustic waves, and modeled through
the coupled mode equations of cavity optomechanics.Comment: 8 pages, 6 figure
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