Abstract
The collector current of actual bipolar transistors in the satulated region increase with the collector voltage. This phenomenon is called the Early effect, and the voltage at which the expolated output curves of bipolar transistors is called the Early voltage. The Early voltgae is usually estimated using the Gummel-Poon model. However the Gummel-Poon model is a little difficult to learn for beginners. In this paper the estimation of the Early voltage using the Gumle-Poom model and that by Taur and Ning are shown. Then the estimation of the Early voltage using the elementary model by the author is shown, and the numerically calculated results are also shown. The estimation using the elementary model may be useful for the begginers to understand the behavior of bipolar transistors.
