差动放大电路输出波形的实验测试方法

摘要

Differential amplification circuit is a key teaching point in the course“Analog Electronic Technology Founda⁃tion”. It is difficult to learn this theory due to there are multiple input/output modes. In addition,it is hard for college students to test the dynamic voltage in single⁃ended output circuit in experiment class due to the differential amplification direct coupling characteristics. The testing method of differential⁃mode and common⁃mode output signal both in double⁃ended output and single⁃ended output modes in differential amplification circuit by using simulation software Multisim detailed is introduced in this pa⁃per. In single⁃ended output,the DC components at output side is tested first without any input signal,and then the differential⁃mode input signal and the common⁃mode input signal are loaded,and the total output of each signal is tested respectively. Final⁃ly the pure differential⁃mode output and pure common⁃mode output signals are obtained by subtracting the DC output component from total output. Thus the differential⁃mode and the common⁃mode voltage amplification factors of a circuit is obtained by calcu⁃lation. This method made up the content lack in the domestic mainstream teaching materials. It can be used as a reference in ex⁃periment teaching. It is also helpful to deepen understanding of the theory in classroom teaching.%差动放大电路是《模拟电子技术基础》课程中的教学重点，由于电路存在多个输入/输出模式而造成了理论学习上的困难，而差功放大电路的直接耦合特性，更是成为大学生在实验课堂上测试单端输出电路中差模与共模输出波形的困惑。这里以Multisim软件仿真的形式，详细介绍差放电路在双端与单端输出模式下差模输出与共模输出信号的具体测试方法，在单端输出时首先测试在零输入情况下输出端的直流成分，然后在输入端加载差模输入与共模输入信号并分别测试总的输出，最后在总的输出中减去零输入情况下的直流输出分量，得到净差模输出与共模输出信号，进而计算得到电路的差模与共模电压放大倍数。该方法弥补了国内主流教材上均没有对此部分内容明确阐述的实际，可作为大学生在差放电路实验中的教学参考，同时也有助于加深对课堂理论教学的理解。