Large-signal HBT model requirements to predict nonlinear behaviour

Measurements and simulations are carried out in order to determine the requirements for a HBT model to predict the generation of harmonics. Unlike, investigations based on Volterra series, also the case of large excitations is investigated, where the load-line reaches through wide ranges of currents and voltages, and self-biasing effects take place. It turns out that in class A operation, it is absolutely necessary for the model to account for the current dependence of the base collector capacitance and collector transit time, even in a set-up where fundamental power and bias points are predicted well also without.