Low actuation voltage cantilever-type RF-MEMS shunt switches for 5G applications

Conventional electrostatic RF-MEMS shunt switches suffer from high actuation voltages, owing to their membrane-type structures with large spring constant. Alternatively, in this work, to alleviate the inherent high actuation voltage requirements of electrostatic shunt switches, we propose a fixed-free cantilever-type RF switch in a shunt configuration and systematically optimize it both from electromechanical and RF performance aspects. The proposed switches are carefully modeled via comprehensive finite element simulations, performed using commercially available solvers i.e., COMSOL and HFSS. The electromechanical response of the proposed switches is optimized by studying three different cantilever designs, where low actuation voltage and switching time of 9.1 V and 90 μs are achieved, respectively. To validate the mechanical reliability of the designed switches, the maximum stress values in switch structures during operation were restricted well below the yield strength of the switch beam. Furthermore, RF performance of the designed switches was optimized for mm-wave regime by maximizing the ratio of switch capacitance in OFF-state and ON-state. The cantilever-type RF-MEMS shunt switch design exhibits an insertion loss as low as −0.065 dB and RF isolation as high as −40 dB, at 30 GHz, demonstrating feasibility for 5G mobile applications. © 2022