Effect of low-frequency noise on the threshold sensitivity of middle-IR photodetectors in a broad frequency range

Low-frequency noise of a photodiode-based photodetector (PD) implementing a transimpedance amplifier scheme has been analyzed. It is found that the low-frequency (drift) noise component in the input chains of modern operational amplifiers makes a decisive contribution to resultant noises of PDs based on A³B⁵ photodiodes at frequencies up to several hundred kilohertz. An illustrative "vector" method of description of the noise characteristics of PD elements is proposed for selecting the optimum type of operational amplifier so as to achieve the final sensitivity and accuracy characteristics at a given response speed.