Nonlinear modelling of dispersive photodiodes based on frequency-and time-domain measurements

This paper presents a concept for the nonlinear modelling of dispersive photodiodes. Different devices such as MSM-, PIN-, and avalanche photodiodes can be described by the same equivalent circuit topology. The model of the photodiode is divided into two parts. A physically based part, which characterizes the generation of electron-hole-pairs and their drift in the depletion layer and an electrical model part, which describes the nonlinear dispersive characteristic of the photodiode by an equivalent circuit. The equivalent network comprises multidimensional charge and current sources similar to known microwave FET modelling approach. Different measurement steps and measurement setups are necessary to extract both physical parameters and electrical model parameters of the nonlinear equivalent circuit. As an example, we use a MSM-photodiode to demonstrate the measurements and extraction method to get the unknown model parameter. We demonstrate the use of the photodiode model to correct the errors, caused by the non-linearities of the photodiode, in a laser radar system.