The base is the thin middle semiconductor layer in a bipolar junction transistor, sandwiched between the emitter and the collector. A small current injected into the base terminal controls a much larger current flowing from the collector to the emitter. The physical thickness and doping concentration of the base region determine the current gain and frequency response of the transistor.
Check the voltage at the base to see if the transistor is actually being driven into saturation.
Related terms
Collector
One of the three terminals of a bipolar junction transistor, responsible for receiving the majority charge carriers.
Emitter
The emitter is one of the three terminals of a bipolar junction transistor.
Bias
A steady DC voltage or current applied to an electronic component to establish its resting operating point.