A new dynamic, self-consistent electro-thermal model of power HBTs and a novel interpretation of thermal collapse loci in multi-finger devices

• Published in: Proceedings of the IEEE 2001 Custom Integrated Circuits Conference (Cat. No.01CH37169) pp. 397 - 400
• Main Authors: Cappelluti, F., Bonani, F., Guerrieri, S.D., Ghione, G., Peroni, M., Cetronio, A., Graffitti, R.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 2001
• Subjects: Bifurcation; Circuits; Electrothermal effects; Equations; Frequency; Gallium arsenide; Heterojunction bipolar transistors; Impedance; Power system modeling; Thermal conductivity
• ISBN: 9780780365919; 0780365917
• DOI: 10.1109/CICC.2001.929809

A new self-consistent dynamic electro-thermal model for power HBTs is presented coupling a circuit-oriented electrical model fitted on experimental data with a full frequency domain thermal model. The thermal model provides the exact frequency behaviour of the device thermal impedance through a quasi-3D approach, rather than a simple single- or multi-pole rational approximation. The self-consistent solution is achieved, in large-signal periodic conditions, through harmonic balance analysis. The dynamic model enables us to discuss the behaviour of thermal collapse in multi-finger devices not only in DC, but also in AC conditions. In particular, a new interpretation is proposed for the thermal collapse loci of such devices in terms of bifurcations, thus providing a simpler and more straightforward stability criterion with respect to those already presented in the literature.