如图1、2、3所示的三种电路是大家熟悉的常用放大电路,但对它们如何进行数学分析和计算呢?等效电路法、四端网路法在这里都有困难。等效电路法物理概念明确,但仅适用于简单的晶体管线性放大器电路,对于复杂电路有时很难画出其等效电路来。四端网路法 The three circuits shown in Figure 1, 2 and 3 are familiar amplifier circuits, but how can they be mathematically analyzed and calculated? The equivalent circuit method and the four-terminal network method all have difficulties here. Equivalent circuit method physical concepts clear, but only for simple transistor linear amplifier circuit, sometimes difficult to draw its equivalent circuits for complex circuits. Four-terminal network law