Linearity and dynamic loadlines of CE and CB SiGe HBTs under the influence of DC bias

Linearity characteristics and dynamic loadlines of common-emitter (CE) and common-base (CB) configuration SiGe HBTs are analyzed and compared at 6GHz under different bias conditions. It is shown that the CB configuration can have both higher power gain and better linearity than the CE configuration under certain bias conditions. Dynamic loadlines of CE and CB configurations are compared and correlated with the linearity of SiGe HBTs under different DC bias conditions. Unlike the CE configuration, of which the linearity characteristic is almost independent of DC bias, it is shown from dynamic loadlines that the linearity of CB SiGe HBTs can be significantly improved by varying the bias conditions