Time-Domain Modeling and Characterization of Capacitive MEMS Switches

Abstract

Capacitive RF MEMS switches present several drawbacks such as high actuation voltages, slow switching times and time-varying performances, due to the deterioration of both their mechanical and electrical properties. Such characteristics justify the interest of the scientific community on the development of accurate measurement techniques to monitor the dynamic behavior of capacitive MEMS switches during continuous actuations. In this paper, a novel measurement system devoted to the time-domain characterization of capacitive MEMS switches is proposed. Moreover, an electrical model for such devices is introduced and its lumped elements are characterized by means of measurement results. The proposed test-bench allows to measure the modulus and the phase of both the incident and the reflected signals of a one-port transmission line based, where the port is represented by the capacitive MEMS device. The paper introduces a software tool based on LabVIEWtrade to compute the capacitance and the resistance values of the model as functions of time. In particular the tool transforms the measured signals in the frequency domain to compute the reflection coefficient by means of components depending on the fundamental frequency of the RF signal, thus neglecting spurious frequency components, out-band noise and harmonics due to interferences