A review on RF micro-electro-mechanical-systems (MEMS) switch for radio frequency applications

This paper is designed to review the MEMS switch by considering key aspects on the basis of mechanical structure, actuation methods, and types of contact and circuit configurations. The cantilevered and clamped-clamped switch structures are explored and discussed. Actuation methods and switch configurations have also been covered to give more insights about their placements and performances in RF systems. The electrostatic and piezoelectric actuation mechanisms can result in fast RF MEMS switches and better reliability but at the cost of increased pull-in voltage. The electrostatic method is mostly employed in MEMS switches due to its distinctive advantages. The resistive switch uses less actuation voltage compare to a capacitive switch but suffers from reliability issue. Nevertheless, the capacitive MEMS switches are prominent in use over ohmic contact switches due to better RF performance and reliabilities by offering lifetime of 3-10 million cycles. The RF MEMS switches can be placed in series, shunt and mixed configurations as per application requirements. Capacitive switches are mostly utilized in RF systems and placed in shunt with coplanar waveguide signal lines. These RF MEMS switches find applications in sensors, resonators, amplifiers, phase shifters, and MEMS satellite vehicles for space applications.