由于激励信号是复数形式的变化量，因此我们还可以采用奈奎斯特准则，利用奈奎斯特图在复平面上的变化特点，对环路增益进行分析。

• This paper suggests that there is another better way to judge whether a system is stable or not-that is analyzing the amplification of loop circuit with the Nyquist rule.