Microwave device modelling for HBT CAD in mobile communications applications

A new electro-thermal physics-based equivalent circuit model for HBTs is described which is suitable for use in CAD of circuits intended for mobile communication applications. The multi-cell electro-thermal equivalent circuit model of an AlGaAs/GaAs HBT is described which is applied to the large-signal microwave characterization of 0.5 Watt power amplifiers for operation at 1.88 GHz. This highly efficient model, which incorporates a new multi-finger electro-thermal model, has been used to perform DC, small-signal and load-pull characterization and investigate parameter-spreads due to fabrication process variations.