What is PNP & NPN Transistor

 PNP & NPN Transistor

PNP Transistor

The transistor in which one n-type material is doped with two p-type materials such type of transistor is known as PNP transistor. It is a current controlled device. The small amount of base current controlled both the emitter and collector current. The PNP transistor has two crystal diodes connected back to back. The left side of the diode in known as the emitter-base diode and the right side of the diode is known as the collector-base diode. The hole is the majority carriers of the PNP transistors which constitute the current in it. The current inside the transistor is constituted because of the changing position of holes and in the leads of the transistor it is because of the flow of the electrons. The PNP transistor turns on when a small current flows through the base. The direction of current in PNP transistor is from the emitter to collector. The letter of the PNP transistor indicates the voltage requires by the emitter, collector and the base of the transistor. The base of the PNP transistor has always been negative with respect to the emitter and collector. In PNP transistor, the electrons are taken from the base terminal. The current which enters into the base is amplified into the collector ends.

 NPN Transistor

An NPN transistor is the most commonly used bipolar junction transistor, and is constructed by sandwiching a P-type semiconductor between two N-type semiconductors. An NPN transistor has three terminals– a collector, emitter and base. The NPN transistor behaves like two PN junctions diodes connected back to back. These back to back PN junction diodes are known as the collector-base junction and base-emitter junction. Regarding the three terminals of the NPN transistor, the Emitter is a region is used to supply charge carriers to the Collector via the Base region. The Collector region collects most of all charge carriers emitted from the Emitter. The Base region triggers and controls the amount of current flows through the Emitter to Collector.