一种微弱电荷检测放大电路设计  

Research and design of weak charge detection amplification circuit

作　　者：杨志文 赵冬青[1] 焦新泉[1] 贾兴中[1] YANG Zhiwen;ZHAO Dongqing;JIAO Xinquan;JIA Xingzhong(National Key Laboratory for Electronic Messurement Tecchnology,North University of China,Taiyuan 030051,China)

机构地区：[1]中北大学电子测试技术国家重点实验室,山西太原030051

出　　处：《电子元件与材料》2019年第2期71-75,共5页Electronic Components And Materials

摘　　要：针对传统电荷放大器对电缆噪声敏感,无法精确测量微弱电荷的问题,设计了一种三运放差动放大电路。通过构建传统电荷放大电路的噪声模型,分析了本底噪声对测量结果的影响,针对其共模特性,设计了三运放差动放大电路,放大微弱电荷同时能有效抑制电缆中的本底噪声,提高电路的共模抑制比。经Multisim仿真和硬件电路实验证明,该电路能实现±1.5 pC微弱电荷的检测放大,在电缆叠加32.8 mV干扰噪声的情况下,输出信号幅值与理论值误差仅为1.3%,进而验证了该电路的可行性与可靠性。Traditional charge amplifier can no longer meet the requirements of detecting weak charges.In response to this problem,a three output differential amplifier circuit was designed.By constructing the noise model of traditional charge amplifier circuit,the influence of background noise on the measurement results was analyzed.According to its common-mode characteristics,a three-op-amp differential amplifier circuit was designed to amplify weak charges while effectively suppressing the background noise in the cable and improving the CMRR of the circuit.The results of multisim simulation and hardware circuit experiment prove that the circuit can detect and amplify the weak charge at the level of+1.5 pC.The error between the amplitude of the output signal and the theoretical value is only 1.3%when the cable is overlapped with 32.8 mV interference noise.The feasibility and reliability of the circuit are verified.

关 键 词：电荷放大器 微弱电荷 差动放大电路 本底噪声 共模特性 共模抑制比 

分 类 号：TN721[电子电信—电路与系统]