Modeling and analysis of an uni-traveling carrier hertero-jucntion phototransistor

In this paper, the equivalent circuit model of UTC-HPT is established to simplify the microwave optical amplifier and mixer design. Based on the equivalent circuit model of HBTs, the photo-generated current in UTC-HPT is introduced reasonably as part of base current. The influence of photogenerated carriers on several equivalent circuit components such as trans-conductance, barrier capacitor, diffusion capacitor and junction resistor are considered carefully in the model. Finally, the collector output current is checked to verify the model validity and the photo-current gain and the photo-characteristic frequency are analyzed with the established model.