Article
Nonlinear Second Order Current Cancellation in HBTs
Solid-State Electronics
(1997)
Abstract
Heterojunction Bipolar Transistor (HBT) has very good linear properties when operated at high frequencies and in large signal modes of operation. In this article we examine the fundamental reasons for such good performance of HBTs, compare various models and look into the influence of different parameters. In particular, cancellation of the second harmonic currents in the base-emitter junction, as proposed by Maas et al.[1], is examined. A set of new analytical expressions is developed for equivalent circuits of varying complexity by using the method of nonlinear currents. We found that the emitter resistance Ree linearizes the HBT at low frequencies by providing negative feedback and by bringing the phase difference of the second order currents closer to 180°. At high frequencies the base collector capacitance Cbc dominates the feedback and its inherent nonlinearity degrades the cancellation of second order currents in the base-emitter junction. Numerical tools are used for comparison and will be needed for future investigations. We have also found an equivalence between what at first appeared to be very different models for current gain.
Disciplines
Publication Date
September, 1997
DOI
10.1016/S0038-1101(97)00075-0
Citation Information
Branimir Pejcinovic and Oliver Woywode. "Nonlinear Second Order Current Cancellation in HBTs" Solid-State Electronics Vol. 41 Iss. 9 (1997) p. 1321 - 1328 Available at: http://works.bepress.com/branimir-pejcinovic/19/