示波器输入电容对上限截止频率测量的影响

单管放大电路是模拟电路中的一个经典实验。通过这个实验,学生可以更好地掌握静态工作点的调整和测试方法,并通过测量放大电路的主要性能指标,体会静态工作点对动态特性的影响。实验电路的上限截止频率仿真值和实测值存在较大差异,本文针对这个问题进行了详细的分析,指出示波器的输入电容是引起差异的主要原因,并进一步讨论了可有的改进测试方法。

Oscilloscope Input Capacity to Higher Cut-off Frequency Survey Influence

The single-valve amplifying circuit is in an analogous circuit＇s classics experiment.Through this experiment,students can well grasp the adjustment and the testing method of the static operating point.Through survey amplifying circuit＇s main performance index,students can also experience the influence of static operating point on dynamic characteristics.There exists a big difference between tested electric circuit＇s higher cut-off frequency simulation value and the actual value.This article makes a detailed analysis of this problem,pointing out that oscilloscope＇s input capacity is the primary cause to the difference,and further discusses the testing method.