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

We present a physics-based multi-energy domain coupled macromodel that allows for the efficient simulation of the dynamic response of electrostatically controlled and viscously damped ohmic contact RF-MEMS switches on the system-level. The predictive power of the macromodel is evaluated w.r.t. white light interferometer and laser vibrometer measurements. Furthermore, the macromodel is, concerning accuracy and performance, benchmarked versus two alternative state-of-the-art system-level models. The results obtained with the presented macromodel are in very good agreement with the measured quasi-static pull-in characteristics as well as the pull-in and pull-out transients. Due to its capability to account for multiple structural modes, the presented macromodel produces, among the evaluated models, the result that is closest to the measured phase of initial contact during dynamic pull-in. Moreover, a detailed experimental evaluation of the damping model shows a very good agreement (maximum relative error does not exceed 10%) for ambient pressures ranging from 960 hPa down to approximately 200 hPa. Compared to other damping models, this constitutes a very good result, especially because the models contain only geometric parameters and no problem-specific fit factors are needed to obtain this accuracy. The resulting macromodel is physics-based and, hence, scalable and predictive. Due to its generic nature it can be - in general - adapted for any electrostatically actuated device working in contact mode.