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Commercial Simulators (commercial + simulator)

Distribution by Scientific Domains
Engineering75%

Selected Abstracts

Analysis of frequency division in microstrip circuits by using the FDTD method

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2008
Oscar González
Abstract The accurate time-domain simulation of the nonlinear dynamics of circuits containing distributed elements is of great interest. Specially at high frequencies, it is essential to consider phenomena, such as crosstalk, packaging effects, and electromagnetic interaction between active and passive elements. These effects are mainly due to the distribute components of the circuit. Therefore, the accuracy in the instability or oscillation analysis of nonlinear circuits is often limited by the models used for such elements. Commercial simulators based on the equivalent-circuit approach hardly take into account the mentioned effects. In this work, the finite-difference time-domain (FDTD) method is applied to the nonlinear simulation of a diode-based microstrip circuit exhibiting a parametric frequency division by two. The FDTD method rigorously solves Maxwell's curl equations in the time domain providing a full-wave characterization of the distributed elements of the circuit. In the example considered, a relatively low operating frequency has been selected to allow a reliable comparison between the results obtained by the proposed technique and those provided by a circuit-based commercial simulator. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1300,1302, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23352 [source]

Analysis and design of passive and active microstrip reflectarrays

INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 5 2003
Francesca Venneri
Abstract The design of reflectarrays is a complex and time-consuming process that very often relies on a trial-and-error approach. In this article, a simplified analysis based on a commercial simulator is proposed. This method, valid for both passive and active antennas, uses a simulator to characterize the single radiating cell and evaluates the contribution of the finite ground plane using physical optics approximation. The proposed design technique has been validated by comparing the simulated response of the single element with the experimentally retrieved phase of the active and passive cell. As a proof of the design concept's feasibility, two small reflectarrays, active and passive, have been prototyped and tested. The measured radiation patterns are presented and discussed. © 2003 Wiley Periodicals, Inc. Int J RF and Microwave CAE 13: 370,377, 2003. [source]

Implementation of the symmetric doped double-gate MOSFET model in Verilog-A for circuit simulation

INTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 2 2010
Joaquín Alvarado
Abstract Recently we developed a model for symmetric double-gate MOSFETs (SDDGM) that, for the first time, considers the doping concentration in the Si film in the complete range from 1×1014 to 3×1018,cm,3. The model covers a wide range of technological parameters and includes short channel effects. It was validated for different devices using data from simulations, as well as measured in real devices. In this paper, we present the implementation in Verilog-A code of this model, which allows its introduction in commercial simulators. The Verilog-A implementation was optimized to achieve reduction in computational time, as well as good accuracy. Results are compared with data from 2D simulations, showing a very good agreement in all transistor operation regions. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Rate-based nonisothermal LLX model and its experimental validation

AICHE JOURNAL, Issue 2 2004
Debjit Sanpui
Abstract Most of the current open literature handles liquid,liquid extraction (LLX) using equilibrium and/or isothermal models. However, in most industrial applications, the assumption of equilibrium and isothermal operation is not reasonable. A rate-based nonequilibrium model for both the mass and energy transfer in LLX during the three distinct stages of drop formation,drop, fall or rise, and drop coalescence,has been developed. These three hydrodynamic phenomena affect the mass transfer between dispersed and continuous phases for which a parallel,parallel mass-transfer resistance model has been incorporated. Because of the very large number of computations associated with repeated calculations of mass-transfer coefficients a local model has been proposed. We have compared our rate-based simulator with two other commercial simulators and our bench-scale experiments have been done for toluene,acetone,water and methyl isobutyl ketone,acetic acid,water systems. Stagewise mass and energy transfer and the hydrodynamics features have been compared between the experimental and the simulation runs. Relative-error square analysis (for the concentration profiles) shows that our simulation results are two orders of magnitude better in comparison to other commercial simulators. © 2004 American Institute of Chemical Engineers AIChE J, 50: 368,381, 2004 [source]