A static large signal model of an Heterojunction Phototransistor SiGe/Si for opto-microwave applications

In this paper a static large-signal model of SiGe/Si double Heterojunction Phototransistor (HPT) based on Ebers-Moll BJT model, is presented, analyzed, and developed for circuits design and simulations. The modeled HPT has been designed and realized in HBT technology from Telefunken Semiconductors foundry. Our model includes many high-order effects to achieve accuracy for most physical phenomena like the avalanche (breakdown characteristics), Webster, Charge storage, Self-heating and Early effects. The validity and the accuracy of the model are assessed by comparing the simulations with the DC measurements which are Gummel plots and Ic-Vce characteristics. A symbolically defined device (SDD) nonlinear flexible model has been implemented in Agilent Advanced Design System (ADS) software, which main parameters are derived directly from the measurements. And it´s designed to predict accurately the DC characteristics over a wide range of operating conditions (biases).