Measurements of Ferroelectric MEMS Microphones

ABSTRACT

This paper introduces three measurement methods of ferro-MEMS microphone in the fields of acoustics, piezoelectronics and mechanics respectively. The results of the three measurements are close to each other in some respects, such as frequency response, resonant frequency, quality value and so on. And they together discover the total characteristics of ferro-MEMS microphone which is hard to be obtained in only one measurement. Especially, a typical TO-CAN packaged ferro-MEMS microphone is presented and coupler measurement technology is discussed for acoustics measurement. Resonance measurement and vibration measurement of microphone membrane are taken mainly to confirm the resonant frequency and frequency response of microphone membrane. All measurement results agree well with theoretical estimation. In the case of ferro-MEMS microphone with membrane size of 2.5 mm × 2.5 mm, the resonant frequency of membrane is 13 kHz, quality factor is about 8. And the sensitivity of the microphone is ?36 dB(15 mV/Pa)@1 kHz.