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针对压电式微传声器的两种测量方法,研究了提高微传声器灵敏度的方法。对于电荷测量法,前置放大电路应采用并联负反馈的方式;对于电压测量法,前置放大电路应采用串联负反馈的方式;并且选用高输入阻抗的放大器作为前置放大器。根据理论推导不同材料在不同测量方法下的灵敏度,发现在电荷测量法下用PZT制备的微传声器与在电压测量法下用ZnO制备的微传声器的灵敏度都比较高。用ANSYS软件对四边固支ZnO压电式微传声器进行静力分析,发现薄膜上最大电压为7.89mV,最小电压为-5.55mV。根据薄膜上的应力分布,针对两种测量方法,优化设计了两种不同的新型微传声器结构。
Aiming at the two measurement methods of the piezoelectric microphones, the method of improving the sensitivity of the microphones is studied. For the charge measurement method, the preamplifier circuit should adopt the parallel negative feedback method; for the voltage measurement method, the preamplifier circuit should adopt the series negative feedback method; and choose the high input impedance amplifier as the preamplifier. The sensitivity of different materials under different measurement methods is deduced according to the theory. It is found that the sensitivity of microphones fabricated by PZT under charge measurement is higher than that of microphones fabricated by ZnO under voltage measurement. ANSYS software for static piezoelectric ZnO microphones fixed on all four sides of the micro-speaker analysis found that the maximum voltage on the film is 7.89mV, the minimum voltage of -5.55mV. According to the stress distribution on the film, two different new microphones structures are optimized for the two measurement methods.