Small-signal lumped-element equivalent model for high operating temperature infrared photodetectors

We present a simple small-signal parameterized equivalent circuit for HgCdTe photodetectors operating at high temperatures in the middle and long wavelength of the infrared spectrum. This circuit is capable of accurate modeling the impedance of these devices upon bandwidth of several GHz and for a wide range of bias voltage and temperatures. We have implemented this model as a parameterized sub-circuit in generic circuit simulator from SPICE family, to study conditions for signal propagation in the photodetector signal path at low level of IR illumination. Analyses based on this model provide a useful insight into photodiode operation.