ABSTRACT
This chapter provides an overview of the vertical bipolar transistor compact model most exquisite transistor model and its capabilities to meet silicon–germanium (SiGe) heterojunction bipolar transistors (HBTs) circuit design challenges. The governing Mextram equations are formulated having in mind NPN transistors, but the model can be equally well used for PNP transistors by simple change of the current and charge polarity. The Mextram has been introduced by De Graaff and Kloosterman at Royal Philips Electronics in 1985. The worldwide interest in SiGe HBTs as a commercial integrated circuit technology is growing rapidly. The corresponding circuit design activities essentially depend on accurate compact models of SiGe HBTs in all relevant modes of the transistor operation. The physical background of the Mextram parameters also provides an excellent framework for the geometrical and configurational scaling. The transfer current is maintained by the electron flow in vertical direction from the emitter contact to the collector buried layer and further up to the collector contact.
