Linear robust photometer circuit

In this paper, a linear photometer circuit based on robust feedback compensation is presented. Here, the photodiode was modelled as a dynamic system and its mathematical model was obtained from the well-known equivalent circuit for a photodiode reported in scientific literature. Next, in order to make the output of the system robust against uncertainties and the inevitable disturbances that corrupt the response of the photometer circuit, a robust feedback controller was designed. Finally, the robust photometer circuit presented in this paper was compared against a conventional photometer circuit based on a transimpedance amplifier. The results of comparing the aforementioned photometers showed that the photometer based on robust control techniques is superior to the one based on the conventional design. The linear robust photometer circuit presented in this paper was used for making measurements of light at 670 nm, its temperature coefficient was very low, and very high sensitivity and linearity characteristics were achieved.