Ebers-Moll Model of a Transistor


  • Promita Ghosh


Ebers, model, Moll, transpor


This article is about the behaviour of a transistor analysed in terms of a two diode model introduced by Ebers and Moll.

To arrive at this model let us first consider the normal operation of a p-n-p transistor with its E-B (emitter-base) junctions forward biased by voltage VEB and the C-B (collector-base) junction biased by any voltage VCB which may be forward bias or reverse bias the C-B junction. The collector current will be given by the part of the input emitter current that reach the collector plus the current flowing through the C-B diode. Thus α is the transistor alpha and the subscript N added to it indicates that we are using the transistor in normal fashion. I is the emitter current, I is the collector current, I is the reverse collector saturation current with emitter open. The negative sign takes into account the actual direction of the current flow.

Suppose we now use the transistor in an inverted fashion with the role of emitter and collector interchanged. In this case we can write where αI is the inverted CB current gain and IEBO is the emitter junction reverse saturation current.

The equations are known as Ebers-Moll equations.


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Fundamental principles of electronics—B.Ghosh



How to Cite

P. . Ghosh, “Ebers-Moll Model of a Transistor”, TEMSJ, vol. 3, no. 2, pp. 84-85, Jul. 2021.