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4 results on '"Fern?ndez, F?lix O."'

1. Behavioral modeling methods for switched-capacitor [SIGMA][DELTA] modulators

Author

Suarez, George, Jimenez, Manuel, and Fernandez, Felix O.

Subjects
Integrators -- Models, Integrators -- Analysis, Dynamic programming -- Usage, Business, Computers and office automation industries, Electronics, Electronics and electrical industries
Abstract

Sigma--delta Modulators ([SIGMA][DELTA]Ms) are cornerstone elements in oversampled analog-to-digital converters and digital-to-analog converters (DACs). Although transistor-level simulation is the most accurate approach known for these components, this method becomes impractical for complex systems due to its long computational time requirements. Behavioral modeling has become a viable solution to this problem. In this paper, we study styles and issues in the accurate modeling of low-power, high-speed [SIGMA][DELTA]Ms and introduce two new behavioral models for switched-capacitor (SC) integrators. The first model is based on the SC integrator transient response, including the effects of the amplifier transconductance, output conductance, and the dynamic capacitive loading effect on the settling time. The second model is based on a symbolic node admittance matrix representation of the system. Nonidealities such as jitter, thermal noise, and DAC mismatch are also addressed and included in a dual-band, GSM/WCDMA, second-order, multibit [SIGMA][DELTA]M model with individual level averaging. VHDL-AMS and MATLAB Simulink were used as modeling languages. Both models are validated against experimental data, showing competitive results in the signal-to-noise-plus-distortion ratio. A comparative analysis between the proposed and a traditional model is presented, with emphasis on the degrading effects due to the integrator dynamics. Moreover, a general simulation speed analysis of the proposed models is addressed. Index Terms--Behavioral modeling, switched-capacitor (SC) integrator, sigma--delta modulator ([SIGMA][DELTA]Ms), Simulink SDM, SC integrator, VHDL-AMS SDM.

Published
2007

3. Behavioral Modeling Methods for Switched-Capacitor ΣΔ Modulators.

Author

Suárez, George, Jiménez, Manuel, and Fernández, Félix O.

Subjects
ELECTRONICS, SWITCHED capacitor circuits, ELECTRONIC circuits, ELECTRIC circuits, ANALOG-to-digital converters, ANALOG electronic systems, DIGITAL-to-analog converters, DIGITAL electronics, TRANSISTORS
Abstract

Sigma-delta Modulators (ΣΔMs) are corner-stone elements in oversampled analog-to-digital converters and digital-to-analog converters (DACs). Although transistor-level simulation is the most accurate approach known for these components, this method becomes impractical for complex systems due to its long computational time requirements. Behavioral modeling has become a viable solution to this problem. In this paper, we study styles and issues in the accurate modeling of low-power, high-speed ΣΔMs and introduce two new behavioral models for switched-capacitor (SC) integrators. The first model is based on the SC integrator transient response, including the effects of the amplifier transconductance, output conductance, and the dynamic capacitive loading effect on the settling time. The second model is based on a symbolic node admittance matrix representation of the system. Nonidealities such as jitter, thermal noise, and DAC mismatch are also addressed and included in a dual-band, GSM/WCDMA, second-order, multibit ΣΔM model with individual level averaging. VHDL-AMS and MATLAB Simulink were used as modeling languages. Both models are validated against experimental data, showing competitive results in the signal-to-noise-plus-distortion ratio. A comparative analysis between the proposed and a traditional model is presented, with emphasis on the degrading effects due to the integrator dynamics. Moreover, a general simulation speed analysis of the proposed models is addressed. [ABSTRACT FROM AUTHOR]

Published
2007
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4. Transformer health indices calculation considering hot-spot temperature and load index

Author

Félix Ortiz Fernández, Fernando Delgado, Inmaculada Fernández, Agustín Santisteban, Andrea Cavallini, Alfredo Ortiz, Universidad de Cantabria, Fernández, Félix O., Ortiz, Alfredo, Delgado, Fernando, Fernández, Inmaculada, Santisteban, Agustín, and Cavallini, Andrea

Subjects
Engineering, Transformer oil, 020209 energy, Dielectric oil, 02 engineering and technology, 01 natural sciences, Temperature measurement, law.invention, Health index, law, Transformers, 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, Electrical and Electronic Engineering, Transformer, 010302 applied physics, business.industry, Electrical engineering, Electrical devices, Electronic, Optical and Magnetic Materials, Reliability engineering, Electromagnetic coil, Hot spot temperature, transformer, business, hot-spot temperature, Overall status
Abstract

The state of a transformer depends on many parameters, which should be taken into account to determine its actual condition. In recent years what is known as health indices of transformers has been defined, which is a practical tool to assess the overall status of these electrical devices. Data from field inspection, laboratory tests, and observations during operation of the transformer are combined. All of these result in an index that provides fairly objective and quantitative information as to the condition of the transformer [1]. The research leading to these results has received funding from multiple sources over years, but we would specifically like to acknowledge the support received in the later stages from the Spanish Plan Estatal de I+D under the grant agreement DPI2013-43897-P.

Published
2017

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