大信号输入二极管电路电流波形分析

实验发现,在低Q点、交流大信号输入情况下,阻容耦合二极管电路的交流电流会出现正、负半周持续时间不等的非线性失真现象。为从理论上分析该现象产生的原因,提出一种新的作图分析法,并基于二极管电流方程进行数学计算,同时采用Multisim 11.0软件进行仿真,结果显示二极管电流由两部分构成：静态电流和正、负半周持续时间不等的交流电流。常规作图法得出的结论＂二极管电流由静态电流和正、负半周持续时间相等的交流电流构成＂在此时不再成立。

Analysis for current waveform of diode circuit with large signal input

The experimental results show that diode AC current waveform in a RC-coupling diode circuit appears nonlinear distortion with different continuance period of positive and negative semi-cycle at low quiescent operation point and under the condition of large AC signal input.In order to explain this phenomenon,a new diagram analysis method is put forward,and a mathematical calculation based on diode current-voltage equation is done.At the same time,the Multisim 11.0 software is used to simulate the circuit,and the results show that there are two components in diode current: one is DC quiescent value,and the other is AC component which is a distortional wave with different continuance period of positive and negative semi-cycle.Thus a conclusion that ″diode current consists of DC quiescent value and AC component which is a distortional wave with same continuance period of positive and negative semi-cycle″ educed from the conventional diagram analysis method is not tenable under the aforementioned working conditions.