提高差分放大电路共模抑制能力的研究

Study on improving the common-mode rejection ability of differential amplifier circuits

为了提高差分放大电路的共模抑制能力,在对差分放大电路理论研究的基础上,采用Multism作为开发平台,分别设计了长尾式差分放大电路和恒流源式差分放大电路的仿真系统。学生只需要调整输入信号,即可获得不同情况下两种差分放大电路的输入输出波形以及动态参数,在改变实验参数的过程中,能够直观地观察出两种差分放大电路的共模抑制能力。经过测试,不论是单端输出还是双端输出,恒流源式差分放大电路对共模信号的抑制能力都远超长尾式差分放大电路,结果与理论保持一致。

In order to improve the common-mode rejection ability of differential amplifier circuit,based on the theoretical research of differential amplifier circuits,simulation system of long tail differential amplifier circuit and constant current source differential amplifier circuit are designed with Multism as development platform. Students can obtain the input and output waveforms and dynamic parameters of the two differential amplifier circuits under different conditions by adjusting the input signals. And in the process of changing experimental parameters,they can intuitively observe the common-mode rejection ability of the two circuits. After testing,whether single or double side output,the constant current source differential amplifier circuit is far more effective than the long tail differential amplifier circuit in the common-mode rejection signal,and the result is consistent with the theory.