Design of a Low Voltage RF MEMS Capacitive Switch with Low Spring Constant

ABSTRACT: This paper reports on the design, testing of a low-actuation voltage Microelectromechanical systems (MEMS) switch for high-frequency applications. In the case of micromachined antennas, which involve low voltage signals, RF MEMS switches with low actuation voltage are required. The actuation voltage of RF MEMS switches mainly depends on the spring constant of the switch membrane. The mechanical design of low spring-constant foldedsuspension beams is presented first, and switches using these beams are demonstrated with measured low actuation voltage. KEYWORDS: Capacitive switch, Low actuation voltage, RF MEMS, Spring constant. I.INTRODUCTION MICROMACHINING and microelectromechanical systems (MEMS) are among the most promising enabling technologies for developing low-power low-cost miniaturized RF components for high-frequency applications. Applications such as cognitive radio system, Multiple-input multiple-output (MIMO) channels and satellite communication need antenna with the reconfigurable parameters The lifetime of capacitive switches strongly depends on the applied actuation voltage for capacitance switches, they experimentally observed a lifetime improvement of a decade for every 5-7-V drop on the switch pull-in voltage In this paper, an RF MEMS capacitive switch with low spring constant operating at a low actuation voltage is presented. II.RF MEMS SWITCHES RF MEMS switches can be classified as capacitive or ohmic on the basis of circuit configuration and as series or shunt based on the nature of contact. The ohmic contact switch consists of a thin metallic strip fixed at one end, suspended over the metallic transmission line with a gap of few microns. A metallic electrode is attached between the transmissio