Monolithic optical sensors based on low shunt resistance p-InAsSbP/n-InAs and p-InAsSbP/n-InAsSb heterostructures grown onto low resistivity n-InAs substrates equipped with trans-impedance amplifiers suffer from output electrical signal distortions. The paper presents analysis of the above distortions and equivalent circuit for output electrical signal analysis and measurements as well as recommendations for suppression of interference of signal components have been suggested.