emitor

Emitor is the term used in several languages to denote the emitter terminal of a bipolar junction transistor (BJT). The emitter is the region that injects charge carriers into the base, providing the main current that flows through the transistor. In an NPN device, the emitter is n-type and injects electrons into the p-type base; in a PNP device, the emitter is p-type and injects holes into the n-type base. The emitter is typically more heavily doped than the base to improve injection efficiency.

In normal operation, the emitter-base junction is forward biased while the base-collector junction is reverse biased in the active region. The emitter current consists of the sum of the base current and the collector current. The transistor’s current amplification is often described by the current gain, beta (β), which relates the collector current to the base current; the emitter current is approximately the sum of those two components.

Emitors in common electronic configurations determine amplifier behavior. A common-emitter amplifier provides substantial voltage gain and moderate input impedance, while an emitter follower (common-collector configuration) offers high input impedance and a voltage gain close to one, with current gain.

Linguistic and nomenclature notes: emitor is a direct translation used in some languages for the emitter, while other languages use emisor (Spanish/Portuguese) or simply emitter (English). The term may appear in textbooks, schematics, and technical discussions without changing the underlying physics. The physical design of the emitter, including doping levels and geometry, influences injection efficiency and overall transistor performance.