Alexandra Stefanescu

Extraction of effective elastic coefficients from a coupled structural electrostatic simulation of a MEMS switch

This paper investigates several methods for the extraction of effective elastic coefficients for integrated micro-electro-mechanical switches, to be used eventually in compact macromodels of these devices. The methods are based on the numerical results obtained from the coupled mechanical-electrostatic finite element (FE) simulation of the device. The best method found is based on a cubic least square approximation of the force-displacement characteristic extracted from the FE simulation. For this method, the relative error of the pull-in voltage is less than 0.5 % with respect to the reference value obtained from the FE simulation. The algorithm of this method is described in detail.

Study of the von Mises stress in RF MEMS switch anchors

In this paper an analysis of the von Mises stress in the RF MEMS switch structures is presented. This study was performed to analyze and optimize the stress in the anchors area for switch structures addressed to K and W frequency bands. Different types of anchors were taken into consideration and a comparison of von Mises stress has been performed. Optimization showed that it is possible to reduce stress up to more than 80% of its baseline, to the values much smaller than the breaking coefficient (100Mpa).

Parametric Models of Transmission Lines Based on First Order Sensitivities

Further downscaling of the integrated circuits pushes the limits of lithographic technologies and certain variability effects previously considered negligible now should be taken into account. This paper proposes an efficient approach that addresses the problem of interconnect process variations. New models for line parameters parameterized with respect to the geometric transversal dimensions, subject to small or large variations are proposed. The parametric models are solely based on the computation of first order sensitivities. In the multiparametric case the use of multiplicative models can be a better choice than the use of traditional models based on first order Taylor Series truncation.

A Novel Graphical Based Tool for Extraction of Magnetic Reluctances Between On-Chip Current Loops

Continued device scaling into the nanometer region has given rise to new effects that previously had negligible impact but now present greater challenges and unprecedented complexity to designing successful mixed-signal silicon. This paper presents a novel graphical tool for semi automatic extraction of magnetic reluctances between on-chip current loops. The novel graphical tool seamlessly integrates within the workflow of the CHAMELEON-RF software prototype developed.

Models for Variability of Transmission Line Structures

The paper is dedicated to the variability analysis of long interconnects, modeled as transmission lines. The subject deals with the numerical extraction of the parametric models for long interconnect. The novelty consists of the parameterization of the p.u.l. parameters of TL models w.r.t. the geometric parameters, subject to large or small variations. Examples of such variations are either due to design or technology (process or lithography), respectively. The accuracy of the simplest first order models is studied and validated experimentally for both affine and rational variability models.

Pressure and temperature determination with micromachined GAN/SI SAW based resonators operating in the GHZ frequency range

This paper describes the experimental development of membrane supported single SAW resonator sensor structures, operating in the 4–12 GHz frequency range. The sensors are manufactured on GaN/Si, using advanced nano-lithographic and micromachining techniques. Rayleigh and Lamb resonance frequency peak shifts vs. pressure and temperature were successfully used for simultaneous determinations of these parameters. Determinations have been performed in the 1–7 Bar pressure range and 20–150°C temperature range. Very high values for the pressure and temperature sensitivities have been obtained, due to the high frequency operation, possible for GaN based SAW type sensors.

Coupled multiphysics-RF reduced models for MEMS

This paper proposes a fast and accurate order reduction algorithm for the extraction of compact macromodels for electrostatic actuated micro-electro-mechanical (MEMS) switches used in radio-frequency (RF) applications. The algorithm uses as input the information obtained from field simulations, in which coupled equations of electrostatic, structural-dynamic, air flow and full wave electromagnetic fields are used. The reduced macromodel is described as a circuit netlist which includes both the electro-structural-fluid flow multiphysics and the RF behavior of the switch. For the benchmark considered, the reduction is impressive, from more than 400000 degrees of freedom of the field models, to a macromodel of order 2 both for the multiphysics part and the RF part. The accuracy is checked by comparing relevant quantities (e.g. pull-in voltage for the multiphysics part and S parameters for the RF part) of the original field model with the same quantities obtained from the reduced macro-model. Relative errors less than 2% are obtained.

Extraction of TL-lumped RF macromodels for MEMS switches

This contribution refers to a methodology for the extraction of RF macromodels for electrostatically actuated switches. The extraction is based on the results obtained from three RF simulations carried out at the device-level model, with the finite integration technique, and use of a fitting procedure based on closed form relationships for the TL-lumped macromodel. Two test configurations were studied and acceptable relative errors in the S-parameters are obtained. Improvements are sometimes possible if a frequency dependent model is adopted for the switch inductivity.

Interactive E-learning on Reduced Order Modeling in Electromagnetics Using COMSON Federated Repository

Continued device scaling into the nanometer region has given rise to new effects that previously had negligible impact but now present greater challenges to designing successful mixed-signal silicon. The European Commission funded Marie Curie Research Training Network “COupled Multiscale Simulation and Optimization in Nanoelectronics”(COMSON) was conceived as a dual purpose research and education platform to simultaneously address nanoelectronic simulation technology challenges and to bridge the human resource gap between industry and academia. The COMSON consortium consists of leading European industrial and academic partners. This short paper presents recent developments in the COMSON federated repository for interactive e-learning on reduced order modeling and optimization in electromagnetics which is used by COMSON academic partners.

Parametric reduced order models in static multiphysics analysis of MEMS switches

This contribution proposes a method to extract parametric reduced models that describe the coupled structural-electric behavior of RF MEMS switches. The equivalent capacitance coefficients and the effective elastic coefficients are extracted from coupled structural-electrostatic analysis. Parametric models are built based on the sensitivities of the extracted equivalent coefficients. The method is validated on two benchmarks: one for which experimental values are available, and the other one from the literature. The results show that, for the tested configurations, even a model of order 1 or 2 can catch accurately enough (e.g. relative error of less than 5 %) the pull-in voltage of the full order model, for a variation of the investigated parameter of less than 20 %. Such a reduced parametric model is useful in early stages of the design.