一种提升超高增益脉冲电流放大电路性能的新方法  

A New Method to Improve the Performance of Ultra-High Gain Pulse Current Amplifier Circuit

作　　者：兰江 李明勇 喻洁 郑舟 买向前 LAN Jiang;LI Mingyong;YU Jie;ZHENG Zhou;MAI Xiangqian(CSIC AlphaPec Instrument(Hubei)Co.,Ltd.,Yichang Hubei 443003,China)

机构地区：[1]中船重工安谱(湖北)仪器有限公司,湖北宜昌443003

出　　处：《传感技术学报》2025年第2期249-255,共7页Chinese Journal of Sensors and Actuators

基　　金：国家重点研发计划项目(2022YFF0706900)。

摘　　要：针对质谱、离子迁移谱、核探测等高端精密分析仪器中pA~nA微弱脉冲电流的放大问题,在传统的电阻反馈型和电容积分型前置放大电路基础上,提出了一种提升超高增益脉冲电流放大电路性能的新方法。该方法利用JFET型晶体管高输入阻抗和超低噪声运放优点,设计了提升脉冲电流放大增益和抑制电容偏差的双通道T型反馈网络,解决了pA级脉冲电流放大中高增益、低噪声、宽带宽相互制约的难题。通过仿真计算并与德国FEMTO公司的DLPCA-200、日本NF公司的CA5351溯源级前置放大器等进行性能对比测试,表明在增益、带宽和噪声方面,新型前置放大电路性能优于DLPCA-200和CA5351,其跨阻增益可达10^(10),带宽≥5 kHz,等效输入电流噪声≤5 fA/Hz^(0.5),可有效提升高增益脉冲电流放大电路的输入阻抗、带宽、带宽一致性、脉冲动态放大等性能。Aiming at the amplification of pA~nA weak pulse current in high precision analytical instruments such as mass spectrometry,ion migration spectroscopy and nuclear detection,based on the traditional resistance feedback and capacitance integrating preamplifier circuits,a new method which can improve the performance of ultra-high gain pulse current amplifier circuits is proposed.This method u-tilizes the advantages of JFET transistor,such as high input impedance and ultra-low noise operational amplifier,to design a dual-chan-nel T-type feedback network,enhancing the pulse current amplification gain and suppressing the capacitance deviation,therefore,solving the problem of mutual restriction of high gain,low noise and wide bandwidth in pA-level pulse current amplification.Through simulating calculation and performance comparison test with DLPCA-200(FEMTO,German)and CA5351(NF,Japan),the new preamplifier circuit shows better performance in terms of gain,bandwidth and noise.Its trans-resistance gain can reach 10^(10),its bandwidth is no less than 5 kHz,and its equivalent input current noise is no bigger than 5 fA/Hz^(0.5),effectively improving the input impedance,bandwidth,bandwidth consistency,pulse dynamic amplification and other performance of high-gain pulse current amplification circuit.

关 键 词：微弱信号检测 高增益脉冲电流放大电路 T型反馈网络 全差分JFET型拓扑结构 超低噪声 

分 类 号：TN72[电子电信—电路与系统]