摘要
为解决电容积分式电流检测法不能满足FAIMS快速测量要求的问题,设计了一种用于FAIMS系统的微电流检测电路。该设计运用I/V电阻反馈法对信号进行放大。通过屏蔽和滤波等设计,有效地降低了FAMIS系统对检测电路的高频电磁干扰。考虑到前端电路的噪声来源,采用合理的元器件和电路设计,运用两级放大将FAIMS系统中的pA级电流放大并转换到mV量级。通过采集卡,利用LabVIEW对测得的电流信号进行采集和数据处理。实验结果表明,该电路的测量精度优于0.1 pA,采样频率高于15 Hz。进行了FAIMS系统实验,测得系统输出的背景噪声为0.2 pA。以乙醇为实验样品,在载气(N2)流量为0.8 L/min的情况下,得到了乙醇的FAIMS谱图,证明了该微电流检测电路可用于FAIMS系统。
In order to solve the problems of the capacitance integral circuit which cannot meet the requirement of fast detection for FAIMS,this paper introduces a new design of circuit for micro current detection in which I/V resistance feedback amplification is used.In this paper,high frequency EMI is decreased effectively by electromagnetic shielding and filter design.Proper components and circuit design are adopted to amplify pA current up to voltage of mV scale with various noise sources of pre-circuit taken into consideration.In experiment,the current signal is collected and processed by NI acquisition board under the control of LabVIEW,and the result shows that the measurement accuracy of the circuit is lower than 0.1 pA and the sampling frequency can reach 15Hz.In the real FAIMS test,the background noise of the sys-tem acquired by the circuit is 0.2 pA and the FAIMS spectra of ethanol is obtained under the condition of carrier gas flow of 0.8 L/min and the compensation voltage from-4 V to 6 V at a 0.1 V sweeping step.The circuit meets well with the requirements of the FAIMS.
出处
《电子测量与仪器学报》
CSCD
2011年第8期711-715,共5页
Journal of Electronic Measurement and Instrumentation
基金
国家自然科学基金(编号:60706030)资助项目
国家自然科学基金仪器专项(编号:20827007)资助项目
