Stability Research of Closed-Loop Gain of Operational Amplifiers in Amplification Circuits

The integrated operational amplifier (referred to as “op-amp” in this paper) is an electronic circuit that is fabricated on a small single-crystal silicon chip using a specific process to incorporate a large number of semiconductor transistors, resistors, capacitors, as well as their interconnections, and has certain functionality. In practice, opamps are commonly used to amplify various weak input signals and mathematical operations output signals. In amplification circuit applications, it is necessary to have a deep understanding of the op-amps' stability in order to make reasonable choices. These decision-making processes involve several issues, such as comparing and evaluating the closed-loop gain stability of individual op-amps and cascaded op-amps, finding the difference between theoretical analysis of closed-loop gain and actual application, as well as understanding the variations in actual gain. This paper analyzes a large amount of experimental data on low-frequency signals using a commonly used op-amp (AD708JN). It investigates the stability and characteristics of closed-loop gain in amplification circuits from multiple perspectives, such as amplification factor, comparison between individual op-amps and cascaded op-amps, and different signal intensities. This paper aims to provide practical references and recommendations for circuit designers.