A heterojunction bipolar transistor (HBT) optoelectronic mixer was studied
experimentally and theoretically. A detailed large signal pi-model and a sm
all signal analysis are described. The frequency dependence of down and up
conversion has been analyzed and measured. In terms of conversion gain, the
advantage of the down conversion process is clearly demonstrated. The valu
es of parameters employed in the mixing process are also discussed for both
large and small signal regimes.