共集电极放大电路高频响应的理论分析和仿真

Theory analysis and simulation of high-frequency response of common collector amplifier circuit

利用EWB软件中的受控源,构建共集电极放大电路的简化高频等效电路,等效电路的直接交流分析仿真与s域源电压增益解析表达式Matlab仿真的数值解、幅频特性、截止频率都吻合很好。源增益和截止频率对晶体管参数β的关系曲线表明,β由小到大引起放大倍数增大,截止频率减小,符合增益带宽积近似不变的结论。

A simplified high-frequency equivalent circuit of CC amplifier circuit was built with controlled source in EWB software. The results of direct AC analysis for the equivalent circuit indicate that results are almost the same with the numerical solution,amplitude frequency character and cutoff frequency of the analytical expression of source voltage gain in S domain with Matlab software. The relation curve of b with source gain and cutoff frequency indicate that the b causes the increase of amplifi-cation factor gradually and decrease of the cutoff frequency,which meets the conclusion that the gain bandwidth product is al-most not changed.