An accurate and compact large signal model is proposed for modeling heterojunction bipolar transistors (HBTs) based on III-V materials. In DC mode, the model includes self-heating, Kirk and Early effects, as well as the temperature dependence of the model parameters. In small signal mode, the model captures the variation of various AC parameters with bias. The procedure of extracting the model parameters uses DC and multiple bias S-parameter measurements. The model is compiled in the HP-ADS circuit simulator as user-compiled model and is verified by comparing its simulations to measurements in all modes of operation for an AlGaAs/GaAs transistor with an emitter area of 2 x 25 mu m(2). (C) 2005 Elsevier Ltd. All rights reserved.