Analysis of the frequency response curve of a differential-type electrostatic actuator

The admittance of one-port electrostatic actuator are modeled using the steady-state sinusoidal response. Also the admittance of the differential type actuator is derived taking the practical conditions into consideration, although it has no admittance in ideal case. It is shown as a function of biasing error, driving error, and capacitive mismatch including parasitic capacitors. The validity of the admittance model is proved by comparing between the admittance model and the measured data. At the end, the distortion in the frequency response curve measured by a capacitive sensor is analyzed and it is concluded that the admittance of the actuator is the main cause of this distortion.