Develop of wideband acoustic sensor

• Main Author: Li,Yueqi
• Other Authors: Zheng Yuanjin
• Format: Thesis-Master by Coursework
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Engineering::Electrical and electronic engineering
• Online Access: https://hdl.handle.net/10356/159532
• Institution: Nanyang Technological University

Acoustic sensors have been widely used in military and commercial equipment due to their superior performance in various aspects. Since the 1980s, research on the production of miniature sensors on silicon wafers using MEMS processing technology has been carried out. According to different working principles and working methods, MEMS acoustic sensors are divided into piezoresistive, capacitive, optical waveguide and other types. Among them, capacitive acoustic sensors have become one of the mainstream acoustic sensors due to its high sensitivity and low noise. MEMS acoustic sensor includes two parts: front sensor and integrated readout circuit. This paper mainly focuses on several basic readout circuit modules and their working principle, including frequency capacitance-to-digital converter, voltage-based capacitance-to-digital converter, SAR-ADC and integrating ADC. In this paper, a readout circuit for capacitive acoustic sensor is designed. The circuit includes a fully differential two-stage operational amplifier and a capacitor voltage conversion circuit. After the circuit verification and simulation, the performance of the circuit meets the design requirements.