模拟开关通道间串扰机理分析及解决办法
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摘要
针对采集系统的多种通道快速切换问题,设计建立了一种动态的等效电路模型,对出现通道间串扰的机理进行定性分析得出出现通道串扰的原因主要来源于电路的输出阻抗过大以及与后续负载的阻抗失配,产生了传输通道信号的前后叠加;通过在模拟开关的输入端进行阻抗匹配并且减小前级输出电阻,使得模拟开关稳定时间常数减小,在有限的采样时间内信号达到稳定状态。测试结果表明此模型可以消除不同通道之间的串扰,能够提高采集系统采集精度和可靠性。
Aiming at the problem of fast switching of multiple channels in the acquisition system,this paper designed a dynamic equivalent circuit model,and qualitatively analyzed the mechanism of crosstalk between channels,after theoretical analysis. The article concluded that the channel crosstalk is mainly caused by the excessive output impedance of the circuit and the impedance mismatch with the subsequent load,resulting in the superposition of the signal of the transmission channel. By impedance matching at the input of the analog switch and reducing the preamplifier's output resistance,so that the time constant of the analog switch was reduced,and the signal reached a steady state within a limited sampling time.The test results show that this model can eliminate crosstalk between different channels and improve the acquisition accuracy and reliability of the acquisition system.
Aiming at the problem of fast switching of multiple channels in the acquisition system,this paper designed a dynamic equivalent circuit model,and qualitatively analyzed the mechanism of crosstalk between channels,after theoretical analysis. The article concluded that the channel crosstalk is mainly caused by the excessive output impedance of the circuit and the impedance mismatch with the subsequent load,resulting in the superposition of the signal of the transmission channel. By impedance matching at the input of the analog switch and reducing the preamplifier's output resistance,so that the time constant of the analog switch was reduced,and the signal reached a steady state within a limited sampling time.The test results show that this model can eliminate crosstalk between different channels and improve the acquisition accuracy and reliability of the acquisition system.
引文
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[4]郭秀兰,张剑英,蔡丽.关于时域法与复频域法求解LTI系统时解的一致性问题[J].电气电子教学学报,2003(4):27-29,40.
[5]文丰,鄢玲玲,李辉景,周畅.基于FPGA的高精度采集模块设计[J].仪表技术与传感器,2017(8):19-22.
[6]成祥.用MOSFET管降低模拟开关中的串扰[N].电子报,2014-03-16(010).
[2]肖天雷.数据采集系统通道间串扰的校准方法[J].上海计量测试,2017,44(6):18-20,23.
[3]陈玉坤,欧连军,冯忠伟,等.飞行器采集系统路际串扰分析和研究[J].宇航计测技术,2016,36(4):68-72.
[4]郭秀兰,张剑英,蔡丽.关于时域法与复频域法求解LTI系统时解的一致性问题[J].电气电子教学学报,2003(4):27-29,40.
[5]文丰,鄢玲玲,李辉景,周畅.基于FPGA的高精度采集模块设计[J].仪表技术与传感器,2017(8):19-22.
[6]成祥.用MOSFET管降低模拟开关中的串扰[N].电子报,2014-03-16(010).