HARMONIC DISTORTION IN SILICON CONDENSER MICROPHONES

The nonlinear effects causing distortion in condenser microphones are investigated and modeled with special attention paid to microphones ma de with silicon micromachining technology. A model of the distortion, based on the quasistatic properties, is described and solved numerical ly using finite differences. The results of the model show that the di stortion is mainly caused by both the inverse relation between the mic rophone capacitance and the deflection of the diaphragm, as well as th e nonlinear electrostatic forces generated by the applied de bias volt age. The results of the model are compared with measurement results on a silicon/polyimide microphone, and good agreement is found. (C) 1997 Acoustical Society of America.