Piezoelectric Microphone with Self-Adaptive Harmonic Distortion Reduction Based on Pressure Compensation Structures

This paper presents a piezoelectric MEMS (Micro Electro Mechanical Systems) microphone designed to adaptively reduce harmonic distortion across a wide range of sound pressure levels (SPL). By incorporating multiple pressure compensation structures, the nonlinear deflection of the sensing membrane is effectively suppressed, leading to a reduction in total harmonic distortion (THD) compared to conventional microphones. To further enhance performance, a ScAlN piezoelectric film with 30 % scandium doping is employed. Experimental results demonstrate that microphones implementing six compensation structures reduce the THD from 8.72 % to 1.91 % at 500 Hz and 170 dB SPL, while the sensitivity remains nearly unchanged from 1.09 to$1.04 \text{mV} / \text{Pa}$. High SPL measurement results further confirm that the microphone can acquire high-fidelity signals without significant waveform distortion. The significant reduction in THD without compromising sensitivity demonstrates that the proposed pressure compensation strategy offers a promising path for developing high-performance MEMS microphones, particularly for high SPL applications.