Abstract:By using the porous piezoelectret film to replace the acousticelectric conversion of conventional electret condenser microphone (ECM), a piezoelectric microphone was fabricated in this work. By making use of the advantage of ultrathin piezoelectret film and the structure improvement, the piezoelectric microphone′s thickness was reduced from 3 mm to 1 mm. We adopted 30 dB gain FET in the microphone′s circuit to solve the problem of low sensitivity. And in order to reduce the influence of parasitic capacitance, we used the single copper PCB. However, when the microphone connected into mobile phone, it subjected to the electromagnetic interference(EMI). After that, we improved the PCB design by using doublesided copper PCB to enhance electromagnetic shielding, and resolved the problem of EMI. Finally, by making use of the waterproof performance of piezoelectret film, and by waterproofing the piezoelectric microphone circuit, the piezoelectric microphone satisfies the IPX7 waterproof standards.