MEMS RF Switches with Ultra-High Switching Speeds

The proposed investigation focuses on the research and development of a fundamentally new, high-speed, radio-frequency (RF) switch. It is designed for frequencies in the range 1-100 GHz. The switch is predicted on thin-film microelectromechanical systems(MEMS) technology with piezoelectric actuation. In general, piezoelectric materials develop strain when an electric field is present, which allows mechanical expansion and contraction of the material to be controlled by an applied voltage. Unliketraditional electrostatic MEMS switches, the closing force between the metal-to-metal contacts can be significantly improved by increasing the bias voltage (electric field strength) across the piezoelectric material. Because the switch restoring force islarge, in-use stiction is greatly mitigated with this architecture. The piezoelectric material lead zirconate titanate (PZT) is used as an actuator in the current project. This makes new mechanical designs feasible. Three strategies are suggested forlowering the switch time constant into the tens of nanoseconds range while preserving other important characteristics of the switch (e.g. high isolation, low resistive losses). These include a bimorph design, piezoelectric extensional bars, andflextensional actuators. Combinations of these strategies are likely to yield a high-performance switch.