Surface Micromachined Microelectromechancial Ohmic Series Switch Using Thin-Film Piezoelectric Actuators

This paper presents results on a surface microma-chined RF microelectromechanical switch that uses piezoelectric actuators. The switch uses solution chemistry-derived lead zir-conate titanate thin films spun deposited onto a high-resistivity silicon substrate with coplanar waveguide transmission lines. Actuation voltages, applied via circuits independent of the RF circuitry, average less than 10 V, with switch operation demonstrated as low as 2 V. The series switch exhibits better than 20-dB isolation from dc up to 65 GHz and as large as 70 dB below 1 GHz. In the closed state, the switch has an insertion loss less than 1 dB up to 40 GHz, limited in this demonstration by substrate losses from the elastic layer used to stress control the piezoelectric actuators. Switching speeds for the different designs are in the range of 40–60 ms. Thermal sensitivity measurements show no change in isolation observed for temperatures up to 125 °C. However, an increase in actuation voltage is required at elevated temperatures.