Characterization of fringing electric field on capacitive RF MEMS switch membrane

In order to obtain the high-fidelity model of self-actuation failure threshold power of the capacitive RF MEMS switch, it is necessary to clear the fringing field effect of the electric field distribution on switch membrane. The area of the switch membrane subjected to RF signal power (ARF) cant be replaced with the switch area over the center conductor (A) in the calculation of expression of self-actuation failure threshold power (Pact) of the switch, because of the influence of the fringing field effect. Otherwise, the deviation of calculation will occur in the RF signal power equivalent voltage (Veq). Therefore, ARF is characterized by using the ratio between the calculated Veq and the Root-Mean-Square voltage (VRMS) of the switch membrane. And ARF/A, a figure of merit (FoM), is constructed to characterize the intensity of the fringing field effect of the electric field distribution on the membrane. The 3D electromagnetic model of self-actuation failure of the switch is constructed using the HFSS (High Frequency Structure Simulator) code. Through the simulation, the distribution of fringing electric field on the membrane in variety of RF signal power (Pin) and air gap of the switch (g0) for the case of a common configuration of the switch is obtained. By comparing the calculation value of FoM and simulation results, the feasibility of using ARF/A, the FoM, to characterize the intensity of the fringing field effect of the electric field distribution on the membrane is preliminarily validated.