Theoretical Calculation and Simulation Analysis of Series Negative Feedback of Differential-operational Amplifier Voltage

A series negative feedback amplifying circuit of the differential op-amp voltage under the direct coupled modes is designed.The voltage gain of basic amplifier is calculated with graphic methods according to the calculating method for a multistage amplifier.Moreover,the voltage gain of a feedback amplifier is also derived by solving the node equations of small-signal equivalent circuit.The results show that the basic relationship of a negative feedback amplifier circuit is satisfied in the two methods.Furthermore,the basic amplifier voltage gain and the feedback amplifier gain are simulated with EWB software.The results indicate that they are same as the theoretical values.The effectiveness of graphic methods applied to feedback amplifier is proved.