The Early effect is the variation in the width of the base in a bipolar junction transistor

Bipolar junction transistor

|- align = "center"| || PNP|- align = "center"| || NPNA bipolar transistor is a three-terminal electronic device constructed of doped semiconductor material and may be used in amplifying or switching applications. Bipolar transistors are so named because their operation involves both electrons...

 (BJT) due to a variation in the applied base-to-collector voltage, named after its discoverer James M. Early

James M. Early

James M. Early was an American engineer, best known for his work on transistors and charge-coupled device imagers. He is also known as Jim Early....

. A greater reverse bias across the collector–base junction, for example, increases the collector–base depletion width, decreasing the width of the charge neutral portion of the base.

In Figure 1 the neutral (i.e.