电阻抗参数成像数据采集系统中三种电流-电压转换器的比较

目的 寻找一种能在2-380kHz间提供2MΩ以上的等效输出阻抗和０.1％以上精度的电压－电流转换电路（ＶＩＣ）。为电阻抗参数成像数据采集系统的建立打下基础。方法 在分别对单运放ＶＩＣ＝三运放ＶＩＣ和由仪表放大器的成的ＶＩＣ的工作原理进行了分析的基础上，根据各自的要求建立了这３个ＶＩＣ，并在不同频率点进行了测量。结果 在低频端，基于仪表放大器的ＶＩＣ具有极高的输出阻抗和很低的噪声水平，在高频时只有三运放ＶＩＣ性能能接近要求。结论 在电阻抗参数成像数据采集系统中应采用三运放ＶＩＣ。

Comparative study on three types of VI converters for data acquisition system of electrical impedance parameter tomography

AIM　To find out a voltage to current converter (VIC) with an output impedance of up than 2 MΩ and a precision of 0.1% at bandwidth of 2～380 kHz for data acquisition system of electrical impedance parameter tomography.METHODS　Based on the analysis of the working principle, three types of VIC were built and the noise level as well as the output impedance at several frequencies was measured. RESULTS　Though the noise level of VIC based on instrumentation amplifier was lower, it also had very high output impedance at lower frequency. But the one, which had the highest output impedance and might meet the needs at high frequency possibly, was three operation amplifiers based VIC. CONCLUSION　The VIC based on three operation amplifiers should be chosen for data acquisition system in EIPT.