An Investigation on Capacitance Modeling of Step Strcture RF MEMS Perforated Shunt Switch

This paper presents the study of capacitance modeling of step structured non-uniform meander based capacitive RF MEMS shunt switch with etched holes on the beam. A new strategy of introducing perforation in the step structure beam minimizes the fringing field capacitance and enhances the switching speed. The switch is simulated using FEM tool for validation and the simulated results of upstate and down state capacitance is compared to the analytical results. Our outcomes reveal that proposed capacitance model defeats the existing models for satellite applications. The errors are estimated and analyzed by varying beam thickness and ligament efficiency. The proposed step structured switch having beam thickness of 1.5um with the minimal dielectric thickness results in high performance of the device with ligament efficiency of $\mu=0.38$ comparing with the benchmark models for capacitance modelling. The proposed analytical model shows extraordinary accomplishment for higher bridge thickness of 1.5μm with an estimation of 0.2-2% error. Two bench mark models of capacitance are calculated and validated against the proposed model.