Condenser microphone performance simulation using equivalent circuit method

This paper presents the analysis of a condenser microphone for use in a hearing instrument and proposes a structure that can be realized using microelectromechanical systems (MEMS) technology. The microphone uses a thin low stress polysilicon with an air gap and a silicon nitride perforated back plate. The aim is to develop the microphones with high sensitivity and low fabrication cost. The equivalent circuit method has been used to evaluate the performance of the microphone. The microphone diaphragm has a proposed thickness of 0.8 μm, an area of 2.6 mm², an air gap of 3.0 μm and a 1.0 μm thick back plate with acoustical ports. A 12.0 volt DC bias voltage is provided between the diaphragm and the back plate. A sensitivity of more than 45.0 mV/Pa is expected for the microphone, with a high frequency response extending to 20 kHz.