Fundamental Difference of Power Handling Between CE and CB HBTs

Abstract

Fundamental power handling of common-emitter (CE) and common-base (CB) (SiGe) power HBTs is compared by measuring their dynamic load lines under large-signal operation with input and output matched for maximum output power (Pout). The distinct difference of load lines indicates the fundamental different power amplification mechanisms between the two configurations. It is shown that under voltage-source bias the CE configuration always provides higher (saturated) output power (Pout) than the CB configuration, while higher power gain and power added efficiency (PAE) could be obtained from the CB configuration than the CE configuration before entering the power saturation region