Parallel-contact metal-contact RF-MEMS switches for high power applications

Electrostatically-actuated metal-contact RF MEMS switches have been designed, fabricated and tested with an aim of handling moderately high RF power (hundreds of mW to 1 W). The design strategy is: (i) the development of a switch element having good metal contacts and reliability without stiction problems under moderate actuation voltage (50-60 V), and (ii) the reduction of RF current through each contact by arranging several mechanically-independent switch elements in parallel. The developed switch element is a relatively wide and thick cantilever having two contacts and should have a contact force of 70 μN per each contact at an applied voltage of 60 V based on the simulation. The measured pull-down voltage of 40-50 V has been obtained. By placing several switch elements in parallel, the insertion loss can be greatly reduced, and a loss as low as 0.03 dB at 2 GHz is obtained for an 8-contact switch (i.e. 4 switch elements) with a corresponding isolation of 22 dB at 2 GHz.