Design, Modeling and Analysis of Perforated RF MEMS Capacitive Shunt Switch

This paper illustrates the design, modeling, and analysis of bridge type structure based capacitive RF MEMS switch with different beam thickness and materials. We have used Ashby's approach to select the best materials in each and every level which helped to improve the overall performance of the switch in terms of mechanical, electrical, and RF properties. Silicon Nitride thin film (epsilon(r) = 7.8) is used as a dielectric material. The beam structure stiffness is analyzed with different materials, such as gold, titanium, and platinum, within these materials gold with high thermal conductivity and Euler-Young's modulus of 77 GPa is offering the best performance. Incorporation of meanders and perforations to the membrane helped to reduce the pull-in voltage. The proposed switch is offering very low pull-in voltage of 1.9 V. The deflection of beam thickness is tabulated for the three materials among them the 2 tm thickness is best beam thickness for the switch for X-band applications. The switch offers best return loss (S-11) of -21.36 dB, insertion loss (S-12) of -0.147 dB, and isolation (S-21) of -52.04 dB at 8GHz. The switch presented in this paper is preferable in X-band applications.