Stabilization of Electrostatic Actuators Through Variable Gain Amplifier

In the presence of high parasitic capacitance, conventional electrostatic actuation methods fail to drive an electrostatic actuator beyond its pull-in point. Although the resonant drive circuit is able to extend the operation range of an electrostatic actuator further at a much lower input voltage, an electrostatic actuator coupled with the resonant drive circuit also undergoes pull-in in the presence of high parasitic capacitance compared to the circuit’s quality factor. To improve its robustness to high parasitic capacitance, we design a variable gain amplifier that reduces voltage gain as an electrostatic actuator moves towards its bottom electrode: the increase in the impedance of the resonant drive circuit reduces voltage gain of a variable gain amplifier through its positive feedback loop, while its negative feedback stabilizes its operation.