On DC modeling of the base resistance in bipolar transistors
Artikel i vetenskaplig tidskrift, 2000

The total base resistance R-BTot constitutes a crucial parameter in modeling bipolar transistors. The significant physical effects determining R-BTot are current crowding and conductivity modulation in the base, both causing reduction of R-BTot With increasing base current I-B. In this paper, it is shown that the reduction of R-BTot(I-B) With increasing I-B is directly related to the physical effect dominating in the base. A new model for R-BTot(I-B) is presented where a parameter alpha is introduced to account for the contributions of current crowding and conductivity modulation in the base. Theoretically, alpha is equal to 0.5 when conductivity modulation is dominant and close to 1.0 when current crowding is the most significant effect. This was verified by measurements and simulations using a distributed transistor model which accounts for the lateral distribution of the base current and the stored base charge. The model proposed for R-BTot(I-B) is very suitable for compact transistor modeling since it is given in a closed form expression handling both current crowding and conductivity modulation in the base. An accurate extraction procedure of the model parameters is also presented.

distributed model

current crowding

bipolar transistor

conductivity modulation

base resistance



Martin Linder

Fredrik Ingvarson

Institutionen för mikroelektronik

Kjell Jeppson

Institutionen för mikroelektronik

Jan Grahn

Shi-Li Zhang

Mikael Östling

Solid-State Electronics

0038-1101 (ISSN)

Vol. 44 8 1411-1418


Elektroteknik och elektronik



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