一种带宽超过200kHz的宽带、电容式、表面微机械加工的全向麦克风。
A broadband, capacitive, surface-micromachined, omnidirectional microphone with more than 200 kHz bandwidth.
作者信息
Kuntzman Michael L, Hall Neal A
机构信息
Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78712.
出版信息
J Acoust Soc Am. 2014 Jun;135(6):3416-24. doi: 10.1121/1.4874620.
A surface micromachined microphone is presented with 230 kHz bandwidth. The structure uses a 2.25 μm thick, 315 μm radius polysilicon diaphragm suspended above an 11 μm gap to form a variable parallel-plate capacitance. The back cavity of the microphone consists of the 11 μm thick air volume immediately behind the moving diaphragm and also an extended lateral cavity with a radius of 504 μm. The dynamic frequency response of the sensor in response to electrostatic signals is presented using laser Doppler vibrometry and indicates a system compliance of 0.4 nm/Pa in the flat-band of the response. The sensor is configured for acoustic signal detection using a charge amplifier, and signal-to-noise ratio measurements and simulations are presented. A resolution of 0.80 mPa/√Hz (32 dB sound pressure level in a 1 Hz bin) is achieved in the flat-band portion of the response extending from 10 kHz to 230 kHz. The proposed sensor design is motivated by defense and intelligence gathering applications that require broadband, airborne signal detection.
本文介绍了一种带宽为230kHz的表面微机械麦克风。该结构采用一个厚度为2.25μm、半径为315μm的多晶硅膜片，悬浮在一个11μm的间隙上方，形成一个可变的平行板电容。麦克风的后腔由移动膜片后方11μm厚的空气体积以及一个半径为504μm的扩展横向腔组成。利用激光多普勒测振仪给出了传感器对静电信号的动态频率响应，结果表明在响应的平坦频段系统顺应性为0.4nm/Pa。该传感器通过电荷放大器配置用于声学信号检测，并给出了信噪比测量和模拟结果。在10kHz至230kHz的响应平坦频段部分实现了0.80mPa/√Hz的分辨率（在1Hz频段内为32dB声压级）。所提出的传感器设计是受国防和情报收集应用的推动，这些应用需要宽带机载信号检测。
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