A methodology for the pull-in voltage of clamped diaphragms

摘要

Due to the electrostatic excitation principle, MEMS based capacitive microphones exhibit a nonlinear behaviour and this communication investigates these nonlinearities with the aim to optimize the input voltage signal. The nonlinear electrostatic force due to the bias voltage is combined with the 2D load-deflection model of a square or circular diaphragm to evaluate the pull-in voltage. An analytical solution is derived to calculate the electrostatic pressure, the pull-in voltage and the deflection profile of the diaphragm. Numerical results with clamped square and circular diaphragms are presented showing the effectiveness of the method.