Macromodel-based simulation and measurement of the dynamic pull-in of viscously damped RF-MEMS switches

Abstract

Three different state-of-the-art approaches are used to generate macromodels of an electrostatically actuated and viscously damped ohmic contact RF-MEMS switch. The capability of the three multi-energy domain coupled models to predict the behavior of the RF-MEMS switch is evaluated w.r.t. white light interferometer and laser vibrometer measurements. The different macromodels show very good agreement concerning the quasi-static measured pull-in/pull-out characteristics. The evaluation of the modeled viscous damping forces demonstrates that tailored physics-based models give significantly better results than simple generic models. However, all approaches fail in capturing the landing phase of the membrane during the dynamic pull-in correctly. Measurements revealed that this is due to the presence of a higher eigenmode that is activated during impact.

A novel comprehensive approach to feedback control of membrane displacement in radio frequency micro-electromechanical switches

“…These forces are applied at the corresponding nodes in the finite element model. TABLE II shows that the modified modal frequency for the first mode (݂ |ୀଵ ) has a calculated value of 14.86 kHz which is in 98.5% in agreement with experimental value found in [3]. The remaining modes are also in good agreement with experimental results.…”

“…A preliminary comparison between the switch fundamental mode of vibration and the experimental one indicates that the SFfree structure has a first modal frequency of 6.89 kHz, while the experimental value for the fundamental modal frequency reported in [3] is 14.7 kHz. This does not necessarily imply any contradiction with existing research at this stage, as neither the squeeze film damping, nor the flexural stiffness of the membrane is taken into consideration at this stage.…”

“…Due to the lack of experimental apparatus to benchmark the outcome of this work against, authors have adopted a switch with published experimental dynamic behavior to base their study on. The adopted switch is identical to that used in [3] and [9] for which the geometry and structural dimensions are presented in Fig.1 and TABLE I. respectively. In this switch, the membrane material is gold with elastic modulus ‫ܧ‬ ൌ 79 GPa, and density ߩ ൌ 19320 kg/m 3 .…”

“…In this switch, the membrane material is gold with elastic modulus ‫ܧ‬ ൌ 79 GPa, and density ߩ ൌ 19320 kg/m 3 . Niessner et al [3] indicated that a dielectric material is applied to the top of the switch electrodes, without mentioning the thickness of the dielectric layer or the dielectric constant, ߳ . In this work, the thickness of the dielectric material ‫ݐ‬ ௗ is assumed to be 0.3 µm of silicon oxide, for which the dielectric constant is ߳ ൌ 3.94.…”

“…In this work, the thickness of the dielectric material ‫ݐ‬ ௗ is assumed to be 0.3 µm of silicon oxide, for which the dielectric constant is ߳ ൌ 3.94. For a complete description of the switch layout and the remaining material properties see [3]. Membrane to base distance ( ) 3.4…”