Design and Analysis of MEMS Piezoelectric Hydrophone Based on Signal-to-Noise Ratio

With the increasing demand for wide-area underwater monitoring, mirco-electro-mechanical systems (MEMS) hydrophones have become indispensable tools for underwater acoustic monitoring due to their cost-effectiveness and miniaturization. However, the low signal-to-noise ratio (SNR) of MEMS hydrophones impedes the acquisition of effective acoustic signals in complex marine environments. Currently, numerous studies focus exclusively on enhancing the sensitivity of MEMS hydrophones, without addressing the simultaneous improvement of sensitivity and noise optimization. This article aims to develop a high-performance MEMS hydrophone by designing and analyzing the chip, preamplifier circuit, and package structure based on SNR. The results indicate that using AlN piezoelectric material and an interdigitated electrode (IDE) structure can enhance the SNR. When the inner circle radius of the electrode is 60% of the diaphragm radius and the boundary of the outer ring electrode is 80% of the diaphragm radius, the SNR achieves optimal performance. A low-noise junction field-effect transistor (JFET) two-stage amplifier circuit is designed to match the output signal characteristics of the MEMS hydrophone chip. Additionally, the high SNR output of the MEMS hydrophone is ensured through an anti-interference and shielding package structure design. Test results demonstrate that the developed MEMS hydrophone exhibits a received sensitivity of −177.6 dB (Ref: 1 V/ $\mu $ Pa) and a noise resolution of approximately 58.4 dB (Ref: $1~\mu $ Pa/ $\surd $ Hz). Compared to similar MEMS hydrophones, it demonstrates higher sound pressure sensitivity and superior noise resolution. The SNR-based analysis and design method can also serve as a reference for developing other high-performance receiving systems.