Pnp And Npn Transistor

TRANSISTOR : A transistor is a three-terminal semiconductor device that amplifies the electronic signals or switches the flow of current. It is an electronic device that that controls the current flow or switches the current flow.

SYMBOL :

upload.wikimedia.org/wikipedia/commons/thum..

NPN TRANSISTOR :

definition:
The NPN transistor consists two n -type semiconductor material which is separated by a thin layer of p-type material.

symbol :

google.com/search?q=transistornpn+symbol+im..

construction : It consists of three terminals :

1. base

2. emitter

3. collector

• The base is the thinnest while collector is the thickest region of the NPN transistor.

• The emitter-base region is in forward biasing and the collector-base region is in reverse biased. google.com/search?q=npn+transistor+biasing&..

Working :

In NPN-transistor,the current flows from collector to emitter because positive supply is given to the base.The NPN-transistor turn-on when the electron enters into the base. In NPN-transistor,the output current exists because of flow of holes.

Majority and minority carriers :

The majority charge carriers in NPN transistors is electron while minority charge carriers is the holes.

Switching Time:

The switching time of NPN transistors is more as compared to PNP transistors because the majority charge carrier is an electron.

Direction of current:

The current flows from collector to emitter.

PNP TRANSISTOR :

Definition: The PNP-transistor consists of two p-type semiconductors material separated by a thin layer of one n type semiconductor.

Symbol :

physics-and-radio-electronics.com/electroni..

construction : it has three terminals.

1. base
2. emitter
3. collector

- The emitter and collector of PNP transistor are made up of p-type material and their base is made up of n-type material.

- The emitter-base junction of PNP transistor is connected in forward biased.

- The collector-base junction is in reverse bias.

Working :

The PNP transistor is turn on when electrons enters into the base. In PNP transistor,output current exists due to flow of electrons.

Majority and Minority charge carriers :

The majority charge carriers in PNP transistor is hole while the electrons are the minority charge carriers.

Switching Time:

The switching time of PNP transistor is less than NPN Transistor because majority charge carrires are the holes.

Direction of current :

The current flows from emitter to collector.