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Page 773 of 938 Results 7721 - 7730 of 9371

Tommaso Addabbo, Ada Fort, Marco Mugnaini, Santina Rocchi, Valerio Vignoli
STATISTICAL CHARACTERIZATION OF A CHAOTIC PIECEWISE LINEAR MAP FOR UNIFORM-DISTRIBUTED ANALOG NOISE GENERATION

In this paper a theoretical approach for studying the effects of parameter perturbations on the chaotic statistics of piecewise linear expanding transformations is summarized, with reference to the chaotic Sawtooth map. On this basis, the authors prove that is possible, both from a theoretical and from an experimental point of view, to obtain almost uniform distributed and uncorrelated analog samples from the Sawtooth map.

Luciano Brunetti, Gian Carlo Bosco, Marco Sellone, Paolo Terzi
BRIDGING A GAP BETWEEN LOW AND HIGH FREQUENCY MEASUREMENTS

INRiM’s primary AC-voltage standard is realized by means of a set of AC-DC Thermal Voltage Converters from DC range up to 1 MHz. Above this frequency, an AC-voltage standard has not been normally implemented because of low technical interest. Indeed, in that range, electromagnetic power, a quantity that is always well definable and measurable also at higher frequencies, becomes more interesting than the AC-voltage. Power standard is realized by means of microcalorimetric technique that, however, lacks in precision under 10 MHz. The result is a metrological gap from 1 MHz to 10 MHz, in which any electrical standard exists, at least at INRiM. To fill this gap a new measurement setup is now under development and characterization, which will allow performing AC-DC Transfer Difference measurement up to 100 MHz and realizing a low frequency power standard. In this paper a description of this new setup will be given together with a set of measurements.

L. Oberto, N. De Leo, M. Fretto, A. Tartari, L. Brunetti, V. Lacquaniti
REALIZATION AND PRELIMINARY MEASUREMENTS ON A 94 GHZ SIS MIXER

In this work we present preliminary results concerning the characterization, in terms of noise temperature, of a 94 GHz prototype receiver based on a superconductive SIS mixer developed at INRIM for the MASTER experiment. It is a tryple receiver for the 94, 225 and 345 GHz bands for astrophysical observations based on SIS Josephson junctions. A promising noise figure of 110 K (about 22 times the quantum limit) has been obtained and contribute in fixing an upper bound to the final overall receiver noise temperature that is compliant with the experiment requirements. Moreover it is not far from the actual state of the art in the field. The realization of the device is also described with attention to the optimization of crucial features along with a DC characterization of its Josephson junctions. Finally, we have demonstrated the INRIM ability to design and realize SIS mixers usable for practical radioastronomical applications.

Konrad Jędrzejewski
MODELLING AND SIMULATION ANALYSIS OF INTELLIGENT PIPELINE A/D CONVERTERS

The paper is devoted to the methods of analysis of a new class of “intelligent” pipeline A/D converters (IP ADC). The conversion scheme used in IP ADC is based on the original approach to optimisation of adaptive estimation systems. Its application to the pipeline A/D converters design enables to improve their characteristics but requires changes in their architecture and principles of conversion. The paper focuses on the modelling and analysis of dependence of IP ADC performance on the parameters of their analogue components and conversion algorithm. The models, methods and simulation tools, proposed and presented in the paper, enable efficient analysis of particularities of IP ADC work and definition of the most appropriate parameters of main components of the converter. They also enable assessment of the expected performance of IP ADC and its comparison with performance of known pipeline A/D converters. The results of selected simulation experiments are presented and discussed in the paper. The presented approach can be used at the initial stages of IP ADC design for effective choice of suitable architecture and parameters of the internal components of IP ADC.

Zbigniew Czaja, Michał Kowalewski
A NEW METHOD FOR DIAGNOSIS OF ANALOG PARTS IN ELECTRONIC EMBEDDED SYSTEMS WITH TWO-CENTER RADIAL BASIS FUNCTION NEURAL NETWORKS

An approach of self-testing of analog parts in mixed-signal embedded systems controlled by microcontrollers is presented. It bases on a dictionary method of detection and localization of single soft faults of passive components in analog electronic circuits. At the Measurement Stage the tested analog part is stimulated by a square impulse generated by the microcontroller, and its response is sampled by microcontroller’s ADC in moments exactly established by an internal timer. Fault detection is made by the two-layer feed-forward perceptron. If the analog part is classified as faulty, the fault localization is performed by the specialized neural network based on Two-Center Radial Basis Functions (TCRBF). Both networks are created and trained on the Before Test Stage on the basis of family of localization belts, which are created by dispersion of identification curves under assumption of components tolerances. Identification curves placed in measurement space illustrate behaviour of the tested analog circuit incoming from changes of values of its components. The proposed method with TCRBF classifier is dedicated for testing and localization of single soft faults in analog electronic circuits. It can also be simply adopted for rough identification of analog circuits’ components.

Ivan Leniček, Damir Ilić, Alan Šala
EXPANSION OF TRACEABILITY CHAIN OF PEL TO HIGH VALUE RESISTANCE STANDARDS

In the Primary Electromagnetic Laboratory (PEL), which is a part of the Faculty of Electrical Engineering and Computing of the University of Zagreb and a part of the Croatian metrology system, the unit of resistance (ohm) is maintained by the group of reference and working standards of nominal decade values ranging from 1 mΩ to 100 GΩ. The group of high value resistance standards from 100 MΩ to 100 GΩ is the hindmost incorporated in the resistance traceability chain, and relies on laboratory developed measurement system for high resistance comparison, which is presented in this paper. Realization of traceability of high value resistance standard group toward both of 10 kΩ and 10 MΩ reference standards is described. Based on 10 MΩ as starting point, the high resistance scaling was performed and temperature coefficients of resistors were determined. The achieved results of high value resistance comparison were analyzed and compared with the calibration values obtained at Physikalisch-Technische Bundesanstalt (PTB).

Wojciech Toczek
PROBABILISTIC EVALUATION OF TEST ARCHITECTURES FOR FULLY DIFFERENTIAL CIRCUITS

The paper presents probabilistic model predestined to the evaluation, comparison and optimization of test architectures for fully differential (FD) circuits. The model have the form of analytical formulae that describe the probability density functions of the signal being measured during testing. The first density function is the generalized form of the Rayleigh distribution. It is relevant for representing a fault-free circuit. The second one is the generalized form of the Rician distribution. It is appropriate for modelling magnitude responses of a faulty CUT as well as a fault-free circuit. The parameters of the models are calculated using Taylor's series approximation method. The model was validated by comparison to the results obtained by Monte Carlo simulation and applied to evaluation of test architectures for a FD bandpass filter. One of the architectures is proposed by the author. The dependence of the probabilistic features of the test responses on the type of testing circuitry and on the testing frequency is demonstrated. It is shown that the testing methods, which exploit common-mode excitation of the CUT, have better probabilistic features than the method, which uses the differential mode excitation.

Jaroslav Strunc, Stanislav Dado
CAPACITIVE SENSOR FOR ROTATIONAL SEISMOLOGY

Studying of rotational components of ground movements belong among emerging approaches in recent geophysics. Rotations can be observed using the dense seismic arrays (microarrays, small aperture arrays) formed from classic three-dimensional seismic sensors. The aim of this project is a construction of portable, high-definition sensor of rotational movement around vertical axis. This sensor is based on measuring of changes of capacitance of differential capacitor.

Ana M. R. Franco, E. Tóth, R.M. Debatin, Rodrigo S. Ribeiro e Bruno C. Couto
A POWER MEASUREMENT SYSTEM UNDER NON-SINUSOIDAL LOADS

The paper gives an account on a new power measuring system, based on digital sampling, which was developed by the National Institute of Metrology (INMETRO) of Brazil. The goal of the project was to achieve the highest possible accuracy at the presence of considerable harmonic distortions, to guarantee full traceability to national standards and to minimize the costs of obtaining a high quality reference system. The system facilitates the calibration of commercialized electronic wattmeters, watt-hour meters, as well as the analysis of non-linear loads, resulting harmonic distortions in power systems.

A. Mariano, D. Dallet, Y. Deval, J-B. Bégueret
NONIDEALITIES STUDY OF A CONTINUOUS-TIME DELTA-SIGMA MODULATOR USING VHDL-AMS MODELLING

In this paper, a complete high-speed Continuous-Time Bandpass Delta-Sigma modulator for digital receiver applications is modeled, using VHDL-AMS. The main Continuous-Time Delta-Sigma modulator’s nonidealities such as excess loop delay, clock jitter and multi-bit feedback DAC element mismatch in the modulator loop are also modeled and their effects evaluated. An accurate understanding of these non-ideal phenomena allows to estimate the limits of the modulator and hence to design more robust building-blocks.

Page 773 of 938 Results 7721 - 7730 of 9371