What is Transistors-:
A transistors are a semiconductor device which basically combination of two P-N junction Diode, that regulates current or voltage flow and acts as a switch or gate for electronic signals. It consist of three layers of a semiconductor material, each capable of carrying a current. A voltage or current applied to one pair of the transistor’s terminals controls the current through another pair of terminals. Because the controlled (Output) power can be higher than the controlling (Input) power, a transistor can amplify a signal.
Type of transistor
Transistors are basically two types:-
- Bipolar Junction Transistor (BJT)
- Field Effect Transistor (FET).
The PNP is another type of Bipolar Junction Transistors (BJT). It consisting of a layer of N-doped semiconductor between two layers of P-doped material, and majority charge carrier in p type semiconductor is hole. A small amount of current leaving the base is amplified in the collector output. In a PNP transistor, the Emitter to Base region is forward biased, so holes are injected into the base as minority carriers. The base is very thin, and most of the holes cross the reverse-biased Base to Collector junction to the collector. The PNP transistor is ON when the base terminal is pulled to LOW with respect to emitter.