一种用于MEMS麦克风的信号采集电路  

Analog Signal Acquisition Circuit for the MEMS Micorphone

作　　者：刘乃瑞[1] 

机构地区：[1]北京青年政治学院计算机系,北京100102

出　　处：《半导体技术》2011年第12期948-952,967,共6页Semiconductor Technology

基　　金：2011年北京市属高等学校人才强教计划

摘　　要：设计了一款用于MEMS麦克风的模数转换接口电路。该电路包含一个前置放大器和一个四阶Delta-Sigma调制器。前置放大器包括一个pMOS输入的源级跟随器和一个仪表放大器。放大器设计中采用了斩波稳定技术消除低频闪烁噪声。Delta-Sigma调制器采用了带有前馈支路的四阶结构,其优点在于低积分器摆幅,可以降低积分器中放大器的非线性增益对电路性能的影响。该电路采用0.18μm CMOS工艺制作,电源电压为1.65μV。测试结果表明,电路可以达到80 dB的动态范围和73.4 dB的峰值信号对噪声加谐波比。电路的耗散电流为1 500μA,占用的芯片面积为0.48 mm2。An analog-to-digital interface circuit for MEMS microphone applications was presented. The interface circuit was composed of a pre-amplifier and a forth-order Delta-Sigma modulator. The preamplifier include a PMOS input source follower which is followed by an instrumentation amplifier. Chop stabilization technique was employed to remove the low frequency flicker noise. The Delta-Sigma modulator is made up of forth-order topology with input feed forward path. The benefit was low integrator swing which mitigates non-linear amplifier gain in the integrator. The prototype interface circuit was implemented in 0.18 μm CMOS technology with the power supply of 1.65 V. Experiment result shows that signal to noise and distortion ratio （SNDR） of 73.4 dB and dynamic range （DR） of 80 dB are achieved. The totai current consumption is 1 500 μA and the core die area of the crcuit is 0.48 mm2.

关 键 词：微机械麦克风 DELTA-SIGMA调制器 斩波稳定 仪表放大器 前馈 

分 类 号：TN432[电子电信—微电子学与固体电子学]