RF MEMS components are biased electrostatically using a bipolar NRZ drive voltage, as shown in Fig. 2, in order to avoid dielectric chargingJ. R. Reid and R. T. Webster: "Measurements of Charging in Capacitive Microelectromechanical Switches," Electronics Letters, vol. 38, no. 24, pp. 1544-1545, Nov. 2002 and to increase the lifetime of the device. Dielectric charges exert a permanent electrostatic force on the beam. The use of a bipolar NRZ drive voltage instead of a DC drive voltage avoids dielectric charging whereas the electrostatic force exerted on the beam is maintained, because the electrostatic force varies quadratically with the DC drive voltage. Electrostatic biasing implies no current flow, allowing high-resistivity bias lines to be used instead of RF chokes.
