Abstract

This paper addresses the issues involved in developing a large-signal heterojunction bipolar transistor (HBT) model with particular emphasis on the role self-heating plays in the parameter extraction process. Starting from a physical analysis of the device, a novel, equivalent-circuit DC model is proposed which models both base and collector currents separately. However self-heating will play a large role in any measurements used in any associated parameter extraction technique developed in conjunction with the model. Therefore a thermal sub-circuit representing the device is first created both from measurements and knowledge of the transistor's physical properties. All DC parameters are then extracted from forward and reverse Gummel plots taken at several ambient temperatures which have had the effects of self-heating removed using a novel "thermal de-embedding" technique. S-parameter measurements made from 45MHz to 20GHz allow for determination of the model's dynamic elements to complete the large signal model. Finally, for verification purposes. DC output characteristics and several single-tone power sweep measured results are given which show good agreement with simulated behaviour.