负反馈对多级放大电路的影响

Effects of negative feedback on multistage amplifier circuit

为了更好地将负反馈引入放大电路,有效地改善放大电路的性能,本文利用Multisim软件对多级放大电路有、无负反馈情况进行了研究.结果表明:有、无负反馈放大电路的直流工作点基本相同;引入负反馈后电路的基本性能得到了较大的改善,但放大倍数减小;负反馈能够较大程度地抑制温度造成的非线性影响;反馈深度愈深,电压放大倍数愈小,对电路的调节能力越强;在一定条件下,负反馈可能变成正反馈破坏放大电路的正常性能.

In order to improve the performance of the amplifier circuit, Effects of negative feedback was studied on multistage amplifier circuit in detail by Multisim. Theresults show that the analysis results of DC operat- ing point is same as non -feedback. When the negative feedback is introduced into the amplifier circuit, the basic performance of the circuit is improved greatly, but the magnification is reduced. It can largely restrain the nonlinear impact of the temperature. When feedback depth is deepened, the voltage magnifi- cation will be reduced, and the adjustment ability of the circuit will be Strenghened. The negative feed- back could become positive feedback and destroy the normal performance of amplifier circuit under cer- tain conditions.