Dielectric Charge Control in Electrostatic MEMS Positioners/Varactors

A new dynamical closed-loop method is proposed to control dielectric charging in capacitive microelectromechanical systems (MEMS) positioners/varactors for enhanced reliability and robustness. Instead of adjusting the magnitude of the control voltage to compensate the drift caused by the dielectric charge, the method uses a feedback loop to maintain it at a desired level: the device capacitance is periodically sampled, and bipolar pulses of constant magnitude are applied. Specific models describing the dynamics of charge and a control map are introduced. Validation of the proposed method is accomplished both through discrete-time simulations and with experiments using MEMS devices that suffer from dielectric charging.