MEXTRAM model based SiGe HBT large-signal modeling

An improved large-signal equivalent-circuit model for SiGe HBTs based on the MEXTRAM model (level 504.5) is proposed. The proposed model takes into account the soft knee effect. The model keeps the main features of the MEXTRAM model even though some simplifications have been made in the equivalent circuit topology. This model is validated in DC and AC analyses for SiGe HBTs fabricated with 0.35-μm BiCMOS technology, 1 × 8 μm2 emitter area. Good agreement is achieved between the measured and modeled results for DC and S-parameters (from 50 MHz to 20 GHz), which shows that the proposed model is accurate and reliable. The model has been implemented in Verilog-A using the ADS circuit simulator.