Large-signal numerical and analytical HBT models

Several large-signal heterojunction bipolar transistor (HBT) models are investigated to determine their usefulness at millimeter-wave frequencies. The most detailed model involves numerically solving moments of the Boltzmann transport equation. A description of the numerical model is given along with several simulated results. The numerical model is then used to evaluate two analytical HBT models, the conventional Gummel-Poon model and a modified Ebers-Moll model. It is found that the commonly used Gummel-Poon model exhibits poor agreement with numerical and experimental data at millimeter-wave frequencies due to neglect of transit-time delays. Improved agreement between measured and modeled data results b including transit-time effects in an Ebers-Moll model. The simple model has direct application to millimeter-wave power amplifier and oscillator design. Several measured results are presented to help verify the simple model