ELECTRO-MECHANICAL OPTIMIZATION OF A LOW-VOLTAGE MEMS-BASED SPDT
F. CHERUBINI, P. FARINELLI, B. BISCONTINI, H. YORDANOV, L. VIETZORRECK, R. SORRENTINO

Abstract. This paper presents the electromagnetic and electromechanical model and design of a MEMS SPDT switch to be integrated in a radio-front end that supports three standards (DCS1800, WLAN 5.2GHz, UMTS 2.2GHz). The switch is based on a coplanar waveguide (CPW) T- junction configuration, employing ohmic contact series switches. It has been first optimized in a very wide band in order to reduce the parasites and electromagnetic couplings by using both circuital and full wave electromagnetic modeling. The validity of the model is demonstrated by comparing the simulated and measured results of a prototype realized at ITC-irst in the frame of an ESA project. The MEMS bridges dimensions and anchor geometry have then been modified in order to lower the actuation voltage as required by the new project specification. Full wave electromechanical simulations show that the switch with the new membrane topology can be actuated by applying about 20V instead of the 50V needed for the actual bridge. The electrical performance of the final structure has been re-optimized in the frequency and 1.8-5.8 GHz in order to use the SPDT switch at different sections of the radio front-end. The switch is going to be manufactured by ITC-irst on high resistivity silicon substrate following the well-established MEMS manufacturing process.