This document discusses the NPN bipolar junction transistor (BJT). It begins with an introduction that explains BJTs use both electron and hole charge carriers and come in NPN and PNP types. It then covers the components of an NPN BJT, how it works using three doped semiconductor regions, its structure, and applications such as amplifiers and sensors. Sample I-V curves are also included, along with references for further information.

1. CAREER POINT UNIVERSITY
MAJOR ASSIGNMENT
TOPIC- NPN BJT
SUBMITTED TO- SUBMITTED
BY-
RAVENDRA MEENA PURVEANK
GUPTA
RAJ
PREMANI

2. CONTENTS:
 INTRODUCTION
 NOTE ON CURRENT DIRECTION
 COMPONENTS USED IN NPN BJT
 HOW NPN BJT WORKS
 FUNCTION
 STRUCTURE
 IV CURVE FOR NPN BJT
 APPLICATIONS
 CONCLUSION
 REFERENCES

3. INTRODUCTION:
A Bipolar transistor junction(bipolar transistor or bjt)is a type of transistor that uses both electron
& holes charge carriers.
BJT are manufactured in two types, NPN & PNP and are available in individual components.
In contrast, unipolar transistors such as field effect transistors, only use one kind of charge
carrier.
For there operation, bjt is used two junctions between two semiconductor types.

4. NOTE FOR CURRENT DIRECTION:
By convention, the direction of current on diagrams is shown as the direction as the positive
charge would move.
This is called conventional current.
Labels for the movement of the holes & electron show there effective direction inside a transistor.

5. COMPONENTS USED IN NPN BJT:
Ammeter
Voltmeter
Base
Emitter
Collector
Voltage source

6. HOW NPN BJT WORKS:
BJT is a semiconductor device constructed with three doped semiconductor regions(base,
collector & emitter).
The p-n junction between the base and the emitter has a barrier voltage (v) about 0.6v which is
an important parameter of the bjt.
Unlike the field effect transistor in which current is produced only by one type of charge carrier.

7. FUNCTION:
BJT comes in two types, or polarities, known as PNP & NPN based on the doping types of the
three main terminals regions.
An NPN transistors comprise two semiconductors junctions that share a thin p-doped anode
region.
NPN BJT with forward biased E-B junction & reverse biased B-C junction.

8. STRUCTURE:
A BJT consists of three differently doped semiconductor regions; the emitter region, the
based region and the emitter region.
The base region is called collector region.
Each semiconductor region is connected to a terminal, approximately labeled :
emitter(E), base(B) & collector(C).

9. IV CURVE FOR NPN BJT:

10. APPLICATIONS:
High speed digital logic
Amplifiers
Temperature sensors
Logarithmic sensors

11. SNAPSHOOT:

12. REFERENCES:
www.wkikpedia.org
www.electrical4u.com
www.allaboutcircuits.com