Direct calculation of the HBT small-signal equivalent circuit with special emphasize to the feedback capacitance

In this paper a new direct evaluation technique for the small-signal equivalent circuit of AlGaAs/GaAs Heterojunction Bipolar Transistors is presented. Based on the known hot and cold measurement technique, all small-signal equivalent circuit elements including the feedback capacitance Cfb can be directly determined in the frequency range from 45 MHz up to 50 GHz without the requirement for any simplification of the corresponding equations.