A Large-Signal Millimeter-wave InP/GaInAs Phototransistor Model: Method of Parameters Extraction and Maximum Gain Investigation

A large signal opto-microwave modeling technique is developed for an InP/GaInAs heterojunction bipolar phototransistor. The DC and RF parameters as well as the optical parameters extraction methods are described. Then an investigation of the maximum available gain is made using three-port considerations to determine the optimal load impedances. Opto-microwave S-Parameters and an opto-microwave gain describing the transfer from the optical input to the electrical output of the phototransistor at millimeter-wave frequencies are defined. This study demonstrates the importance of the base load impedance on the opto-microwave transfer from the optical input to the collector output of the InP/GaInAs heterojunction bipolar phototransistor, and therefore on the phototransistor responsivity.