CMUT电流信号的转化放大与滤波电路设计

Design of Amplifying and Filtering Circuit of CMUT Current Signal

针对电容式微机械超声换能器(CMUT)高灵敏度、宽频带的特点以及微弱电流检测的需求,设计了一种高增益、宽频带的三级放大电路,实现对CMUT器件的微弱电流信号的检测、放大以及滤波功能。通过搭建测试系统平台,实现CMUT对水下超声信号的接收,对电流信号接收放大与滤波,同时对电路性能进行测试验证。实验结果表明,电路可以对CMUT器件产生的微弱电流信号进行转换放大和滤波,增益可以达到130 dB以上,同时前两级电路结构的带宽也可以达到10 MHz,涵盖了CMUT的工作频带。测试结果表明,第一级与第二级电路结构具有良好的线性度与稳定性,第三级电路结构的测试结果与仿真结果具有一致性,该电路可以对CMUT发出的微弱电流信号进行转化、放大和滤波。

Aiming at the demand of high sensitivity,wide band and weak current detection of capacitive micromachined ultrasonic transducer(CMUT),a three-stage amplifier circuit with high gain and wide band was designed to realize the detection,amplification and filtering functions of weak current signal.By building a test system platform,it can receive underwater ultrasonic signals of CMUT devices,the circuit can receives,amplifies,filters current signals,and the circuit performance is tested and verified.The experimental results show that the circuit can convert,amplify and filter weak current signals generated by CMUT device,the gain can be over 130 dB.Meanwhile,the bandwidth of the first two circuit structures can also reach 10 MHz,covering the working frequency band of CMUT.The test results are highly consistent with the simulation results,and the circuit can transform,amplify and filter the weak current signal from CMUT.