The effects of distributed base potential on emitter-current injection density and effective base resistance for stripe transistor geometries

Simple analytic expressions are derived for the variation of base current, emitter current and emitter-base voltage along the emitter junction of a transistor structure due to the flow of dc base current parallel to the emitter junction. The effective width of the emitter region is discussed, and it is shown that as the emitter width is increased, the effective emitter width approaches a constant value. The change in base resistance with emitter current is also calculated. The use of base contacts on each side of an emitter region is discussed and the analysis is shown to be applicable to this problem for equal or unequal division of base current between the two contacts. The results are applied to a planar transistor structure.