The Early effect describes how an increase in the reverse-bias voltage across the collector-base junction of a bipolar junction transistor (BJT) expands the depletion region. This expansion reduces the effective width of the neutral base region. As a result, the transistor's current gain increases slightly with higher collector voltage, preventing the device from acting as a perfect current source.
Heard on the job
You can see the Early effect on the curve tracer because the collector current lines slope upward instead of staying perfectly flat in the active region.
Also heard as
- base-width modulation