ABSTRACT
One of the remarkable characteristics of SiGe heterojunction bipolar transistors (HBT) is the ability to operate over a wide temperature range, from as low as sub 1 K to as high as over 400 K. This chapter summarizes progress in wide temperature range SiGe HBT compact model development. A logical starting point toward wide temperature range modeling is to take an existing SiGe HBT compact model, and modify the temperature scaling or mapping equations of model parameters to “fit” measurement data over a wider temperature range. An important temperature effect to model is freeze-out, which affects T-dependence of resistances, junction built-in potentials, as well as the avalanche multiplication factor. An excellent circuit that can be used to test temperature scaling capability of transistor DC current modeling is the bandgap reference (BGR). BGRs are extensively used in a wide variety of circuits and have been demonstrated to work well at cryogenic temperatures.
