A Novel Three-State Contactless RF Micromachined Switch for Wireless Applications

This letter presents a novel three-state contactless radio frequency (RF) microelectromechanical systems switch for wireless applications. The switch is free from stiction and charge injection issues occurred inherently in contact-type RF MEMS switches, thereby increasing reliability and lifetime. The contactless switch is based on variable capacitance between signal lines and movable grounded electrodes controlled by electrostatic actuator. The movable grounded electrode has the capability to move bidirectionally, and therefore, the switch can change among ON-, OFF-, and deep OFF-states. Thus, additional isolation can be achieved in the deep OFF-state. The RF measurement results show that the contactless switch has a capacitance tuning ratio of 5.25 between OFF- and ON-states, and a higher tuning ratio of 11.18 between deep OFF- and ON-states. In addition, the switch exhibits -3.62 dB insertion loss and -24.43 dB isolation at 2.4 GHz. At 5 GHz, the insertion loss and isolation are -2.95 dB and -20.65 dB, respectively.