差分-共基负反馈放大器的理论计算与微变等效电路仿真

The Theoretical Calculation and Simulation of Micro-change Equivalent Circuit of Differential Common Basis Feedback Amplifier

在利用稳压二极管特性,解决直流电平配置和信号有效输入的基础上,设计差分-共基电流并联负反馈放大电路.采用方框图分析法,对基本放大器做静态电流计算,进而得晶体管等效电阻和微变等效电路.微变等效电路仿真结果与理论计算一致,表明满足反馈放大器中基本关系.将开、闭环下的反馈放大器仿真所得输入电流、输出电流、反馈电流分别做比,得开环增益、闭环增益和反馈系数,同样满足反馈中的基本关系.等效电路与反馈放大器两种电路的仿真结果基本一致,说明方法的正确性.

with using the character of voltage stabilizing diode to solve the basic DC level configuration and amplify input signal, differential common basis parallel connection negative current feedback amplifier circuit is designed in the paper. The block diagram analysis method is adopted to calculate the static current of the amplifier, and the equivalent resistance and micro-change equivalent circuit of the transistor are derived. The simulation results of micro-change equivalent circuit is almost the same as theoretical values. This indi- cates that the basic relation of feedback amplifier is satisfied. By comparing of input current, output current and feedback current which are derived by simulation for open loop and close loop of feedback amplifier, the open loop gain, close loop gain and coefficient of feedback are derived. They also satisfy the basic relation of feedback. The correctness of the method is proved by the consistent results of equivalent circuit and feed- back amplifier.