Electro-parameter model of photodiode and stability analysis of I/V conversion circuit

To overcome the instability of I/V conversion circuit caused by parasitic parameters of photodiode and increase the accuracy for weak photocurrent detection of the photodiode, this paper presents a real electro-parameter model of photodiode, and analyzes the reason for oscillation of the photodiode detection unit affected by the real electro-parameter. With the method of lead-compensation, the phase shift caused by the junction capacitor and the input capacitor of OP Amps in the real model of the photodiode detection unit, is compensated. Simulations of the model and circuit as well as experiments are presented in this paper. The results show that the method can effectively suppress the oscillation in the photodiode I/V conversion circuit, which improves the precision of weak photocurrent detection.