SiGe HBT Parameter Extraction Using Mextram 505.00

Abstract

Applications of SiGe HBT need a robust model which can accurately describe the performance of SiGe HBT at various temperatures. Circuit simulation requires accurate transistor model and reliable parameters.

This work presents SiGe HBT parameter extraction using the latest version of Mextram (Most EXquisite TRAnsistor Model) 505.00. A first generation SiGe HBT with 50 GHz cut-off frequency is used to show the extraction procedure using ADS simulator and extraction software IC-CAP.

Low current model parameters are first extracted at reference temperature, including capacitance parameters, Early effect parameters, avalanche parameters, saturation currents, from low current $I-V$ or $C-V$ characteristics, where self-heating is negligible. Temperature scaling parameters of these low current model parameters are then determined by fitting low current $I-V$ at all temperatures. Next, high current model parameters at reference temperature are extracted, including series resistances, self-heating thermal resistance, epi-layer model parameters, avalanche current dependence. Simultaneous fitting of high current characteristics at all temperatures is used to determine or refine temperature scaling parameters for high current parameters. Following this strategy, the extraction results show that simulated curves are well correlated with measured data.