Defects Simulation of Optocoupler Based on Low-Frequency Noise Analysis

Optocoupler is widely used in the field of aerospace and military, its reliability is attached more importance. Current transfer ratio (CTR) is a conventional electric parameter used to evaluate its reliability. But it can not reflect microscopic changes of device internal defects directly. In order to study the influence of defects to output noise, defects simulation of optocoupler based on low-frequency noise analysis was presented in this paper. Firstly, optocoupler Defects was analyzed. By formulas derivation, the relationship between low frequency noise and defects was obtained. An equivalent model of optocoupler was built on the foundation of noise characteristic. Parameters can be adjusted according to equipment or data sheet. Finally output noise and CTR were analyzed via changing parameters inner the test circuit. It can be seen from the simulation results that when defects amplified and traps inner optocoupler increased, the output noise is responded sensitively, 1/f noise increased along with the number of defects in low frequency range. Simulation results indicated that the method used low frequency noise as an effective way to evaluate the reliability of optocoupler presented in this paper is feasible.