Page "Distributed element model" Paragraph 8

Another example of the use of distributed elements is in the modelling of the base region of a bipolar junction transistor at high frequencies.

The analysis of charge carriers crossing the base region is not accurate when the base region is simply treated as a lumped element.

A more successful model is a simplified transmission line model which includes distributed bulk resistance of the base material and distributed capacitance to the substrate.

This model is represented in figure 2.