Robust Design of RF-MEMS Cantilever Switches Using Contact Physics Modeling

Abstract

This paper presents the design optimization of a RF MEMS direct contact cantilever switch for minimum actuation voltage and opening time, and maximum power handling capability. The design variables are the length and thickness of the entire cantilever, the widths of the sections of the cantilever, and the dimple size. The actuation voltage is obtained using a 3D structural-electrostatic FEM model, and the opening time is obtained using the same FEM model and the experimental model of adhesion at the contact surfaces developed in our previous work. Since the precise control of the contact resistance during the micro machining process is practically impossible, the power handling capability is estimated as the ratio of the RMS power of the RF current (signal") passing through the switch to the contact temperature ("noise") resulting from the possible range of the contact resistance. The resulting robust optimization problem is solved using a Strength Pareto Evolutionary Algorithm, to obtain design alternatives exhibiting different trade-offs among the three objectives. The results show that there exists substantial room for improved designs of RF MEMS direct-contact switches.