Compact RF Model for Transient Characteristics of MEMS Capacitive Switches

A compact model is proposed to facilitate the design and simulation of the control waveform of RF microelectromechanical systems (MEMS) capacitive switches with electrostatically actuated membranes. Following conventional approaches, the pull-in motion of a membrane is simulated by an L-R-C network. However, the present model deviates from conventional approaches by adding another capacitor and a diode to simulate the gradual contact of the membrane with the stationary electrode. After contact, variable mass, spring constant, and damping factor are used to simulate the release process of the membrane. By smoothly bridging the model between pull-in, contact, and release processes, the model can efficiently simulate static and transient S-parameters of the switches up to 50 GHz. The model can be readily installed in popular computer-aided circuit design environments to analyze in the time domain the behavior of the switches and the operation of MEMS-based circuits.