A new thermal model for HBT RF circuit simulation

A simple thermal model for heterojunction bipolar transistors was implemented in the HP EEsof LIBRA simulator. The model is based on a proposed circuit that adjusts the Libra's built-in Gummel-Poon model. Thermal effects are properly simulated, giving a good agreement for DC I-V characteristics, small signal S parameters and for power curves at 1.85 GHz signal. A nonlinear dependency of the thermal effect with RF power is observed on the power curves and is properly modeled.