2012•Journal of Hefei Normal UniversityRequires access
The Theoretical Calculation and Simulation Analysis of Operational Amplifier-Differential voltage with Series Negative Feedback
Wu Long
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Abstract
By using the analysis method of block diagram and aiming at the designed operational amplifier-differential voltage amplifier circuit of the direct coupling mode with series negative feedback,the voltage gain of the basic amplifier is calculated by adopting the calculation method of multistage-amplifier gain,and then the voltage gain is obtained based on the basic relationship of the feedback amplifier.In addition,by using the small-signal equivalent circuit method,the voltage gain of the negative feedback amplifier is calculated through respectively replacing the operational amplifier and the crystal triode by voltage-controlled voltage source and current-controlled current source,both of that meet the basic relationship of negative feedback amplifier circuit.At the same time,the output voltage of the basic amplifier and the feedback amplifier are measured by using the simulation software EWB.Therefore the voltage gain is gotten by dividing the output voltage with the input voltage.By comparing the measurement results with the theoretical values,the maximum relative error is less than 0.175%.The analysis results above show that the method adopted in this paper is correct.