Ebers-Moll Model is an ideal transistor model which describes the operating regions (states) of a transistor. This model is very useful to obtain the information about DC characteristics of a transistor. The transistor operates in active region when emitter junction is forward biased and collector junction is reverse biased. This model generalizes the behaviour of transistor by taking into account the inverted mode of operation of transistor.
Device modelling aims at relating physical device parameters to device terminal characteristics. Device modelling is especially important for integrated circuits. Since simple and accurate device models are required to predict the performance of a circuit.
The dependence of the currents in a transistor upon the junction voltages, or vice-versa may be obtained by
For the Inverted mode of operation,
Where, αi is the inverted Common-base current gain
Ieo is the emitter junction reverse saturation current
Ve is the voltage drop from P-side to N-side
Ebers-Moll Model for a PNP Transistor
The above figure shows the Ebers-moll model for a PNP Bipolar Junction Transistor (BJT). It involves two ideal diodes placed back to back with reverse saturation currents -Ieo and -Ico and two dependent current controlled current sources shunting the ideal diodes. This model is valid for both forward and reverse biased static voltages applied across the transistor junctions.