Design and Frequency Response Study of the Output Stage of an Analog Optoelectronic Amplifier

Abstract

The paper presents the theoretical foundations of a galvanically isolated analog amplifier built on the HCNR200 high-linearity analog optocoupler and the OPA354 operational amplifier. The transfer coefficient is derived for the input feedback loop and the output transimpedance stage, and the frequency response of the transimpedance stage is analyzed using a second-order model. Calculations performed in the MATLAB environment with the parameters taken from the manufacturers’ datasheets show that increasing the feedback resistor from 10 kΩ to 1 MΩ raises the transimpedance by 40 dB, while the −3 dB bandwidth decreases from approximately 5.9 MHz to 0.77 MHz. A procedure for selecting the compensation capacitor is given.