Decoupled electrical/thermal modeling of AlGaAs/GaAs heterojunction bipolar transistors

We describe a decoupled approach to modeling self heating effects in HBTs where we solve for average thermal impedances in three dimensions and solve the electrical problem at three fixed temperatures in two dimensions, then we find the self consistent solution of the temperature rise and current equations. Results are given for thermal impedances of thermally-shunted HBTs. Measured forward Gummel IV curves, IV curves for forced base currents, f/sub t/ values, and breakdown characteristics are compared with the model.