Heterojunction bipolar phototransistors for analog microwave photonic systems

The Heterojunction Bipolar Transistor (HBT) commonly used in GaAs MMICs for microwave and millimeter wave systems can perform as a high speed photodetector with inherent gain and high linearity. The use of the phototransistor will allow circuit designers to develop a new class of photonic/millimeter wave circuits. A new model for the HBT has been developed which solves for the electrical and photogenerated currents. Experimental and theoretical curves relating to the device behavior are presented and compared.