An analytical SiGe-base HBT model and its effects on a BICMOS inverter circuit

Reports an analytical model for SiGe-base HBTs with a graded germanium profile in the base region and its effects on the rise time in a related BiCMOS inverter circuit. According to the model results, for an HBT with a graded germanium profile, a peak germanium concentration of 15% at the base/collector junction is sufficient to generate an optimized forward transit time. For a BiCMOS inverter using linearly graded SiGe-base HBT's with a peak germanium concentration larger than 15% at the base/collector, its rise time is not strongly correlated to its peak germanium concentration.<
>