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Tlaxcala, Mexico

Sanchez-Lopez C.,UAT | Fernandez F.V.,IMSE CSIC | Tlelo-Cuautle E.,National Institute of Astrophysics, Optics and Electronics
Microelectronics Journal | Year: 2010

This paper proposes new admittance matrix models to approach the behavior of fully-differential Operational Transresistance Amplifiers (OTRAs) and Current Operational Amplifiers (COAs). The infinity-variables method is used in order to derive the new generalized models. As a consequence, standard nodal analysis being improved to compute fully-symbolic small-signal characteristics of fully-differential analog circuits. © 2009 Elsevier Ltd. All rights reserved.


Tlelo-Cuautle E.,National Institute of Astrophysics, Optics and Electronics | Sanchez-Lopez C.,UAT | Moro-Frias D.,National Institute of Astrophysics, Optics and Electronics
International Journal of Circuit Theory and Applications | Year: 2010

New nullor-based models are introduced to describe the behavior of the first generation current conveyor (CCI), second generation current conveyor (CCII), third generation current conveyor (CCIII), their inverting equivalents (ICCI(II)(III)), and/or their multiple output topologies (MO(I)CCI(II)(III)). These nullor equivalents include only grounded resistors to improve the formulation of equations in symbolic nodal analysis. In this manner, it is highlighted the usefulness of the proposed models to calculate analytical expressions in MO(I)CCI(II)(III)-based analog circuits. Copyright © 2009 John Wiley & Sons, Ltd.


Trejo-Guerra R.,National Institute of Astrophysics, Optics and Electronics | Tlelo-Cuautle E.,National Institute of Astrophysics, Optics and Electronics | Sanchez-Lopez C.,UAT | Munoz-Pacheco J.M.,UPP | Cruz-Hernandez C.,CICESE
Revista Mexicana de Fisica | Year: 2010

Multiscroll chaotic attractors are physically implemented by using commercially available current-feedback operational amplifiers (CFOAs). The values of the circuit elements are obtained systematically by a proposed technique based in the saturation of the CFOA to create Piece-Wise Linear (PWL) functions. Herein the technique is verified by Spice simulations and in experimental form by using CFOAs to generate n-scroll attractors in a systematic way. Lyapunov exponents are given to prove the chaotic behavior.


Sanchez-Lopez C.,UAT | Fernandez F.V.,University of Seville | Carbajal-Gomez V.H.,National Institute of Astrophysics, Optics and Electronics | Tlelo-Cuautle E.,National Institute of Astrophysics, Optics and Electronics | Mendoza-Lopez J.,University of Seville
International Journal of Nonlinear Sciences and Numerical Simulation | Year: 2013

Existing models of continuous nonlinear functions used for generating multi-scroll chaotic attractors are based on a piece-wise linear (PWL) approach. These models, although relatively easy to build, do not include any information related to the performance parameters of active devices, in the context of a possible physical implementation. This is a serious drawback, since the use of a PWL model introduces a level of inaccuracy into a numerical analysis which is more evident when numerical and experimental results are compared. This paper proposes a methodology to generate the behavioral model of continuous nonlinear functions, but unlike PWL approaches, real physical active device parameters are herein taken into account. In particular, we generate the behavioral model of a nonlinear function called saturated nonlinear function series (SNFS), but in general, the proposed approach can be used to generate the behavioral model of other continuous nonlinear functions. Our results indicate that the proposed approach yields a more realistic and accurate behavioral model than PWL models. As a consequence, not only the generation of chaotic attractors is more precise, but the metrics used to measure the complexity of a chaotic system can also be better predicted. Numerical and electrical simulation results at both domains, phase and time, illustrate the benefits of the new proposed model.


Trejo-Guerra R.,National Institute of Astrophysics, Optics and Electronics | Tlelo-Cuautle E.,National Institute of Astrophysics, Optics and Electronics | Munoz-Pacheco J.M.,UPP | Sanchez-Lopez C.,UAT | Cruz-Hernandez C.,CICESE
International Journal of Nonlinear Sciences and Numerical Simulation | Year: 2010

A challenge in the physical design of n-scroll attractors is to generate a large number of scrolls. However, an open question is: Does the large number of scrolls determine a better chaotic behavior? We present a partial answer to this question by computing the Lyapunov exponents for piecewise-linear (PWL) functions based on n-scroll third order chaotic oscillators, namely: Zhong modified Chua's circuit, Yu modified Chua's circuit, saturated function series based chaotic oscillator, and generalized Chua's circuit with saw-tooth function. Three different integration methods (forward Euler, fourth order Runge Kutta and Matlab© ODE 45) are used in order to show that the positive Lyapunov exponent is not significantly incremented in relation with the number of scrolls. ©Freund Publishing House Ltd.

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