Question

what is a pnp transister??

Answer 1

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 symbol of PNP transistor is shown in the figure below. The inward arrow shows that the direction of current in PNP transistor is from the emitter to collector.



Construction of PNP Transistor

The construction of PNP transistor is shown in the figure below. The emitter-base junction is connected in forward biased, and the collector-base junction is connected in reverse biased. The emitter which is connected in the forward biased attracts the electrons towards the battery and hence constitutes the current to flow from emitter to collector.



The base of the transistor is always kept positive with respect to the collector so that the hole from the collector junction cannot enter into the base. And the base-emitter is kept in forward due to which the holes from the emitter region enter into the base and then into the collector region by crossing the depletion region.