TRANSISTORS

“The building blocks of electronics world”

This session will help you to understand the, 1.Evolution of transistor  2.Importance of transistor  3.Definition & transistor types  4.Transistor symbol & operation  5.Advantages of transistor

6.Latest in transistor technology

History of transistors In 1906, an American inventor and

physicist, Lee De Forest, made the vacuum tube triode or audion as he called it.

Used in radios Used in early computers

The first transistor

In 1947, John Bardeen and Walter Brattain deviced - the first "point contact" transistor.

Moore’s Law

It’s an observation made by Gordon E. Moore, in which he predicted that the number of transistors, inside an Integrated Circuit, could be doubled every 24 months.

At the density that also minimized the cost of a transistor.

Transistor DefinitionTransistor is an electronic device made of three layers of semiconductor material that can act as an insulator and a conductor.

The three layered transistor is also known as the bipolar junction transistor.

Bipolar Junction Transistors (BJT’s)

The term bipolar refers to the use of both holes and electrons as charge carriers in the transistor structure

There are two types of BJTs, the NPN and PNP

Basic construction

Regions of a transistorA transistor has three regions namely,

Emitter- heavily doped

Base- lightly doped

Collector- moderately doped

Transistor symbols Transistor symbols

Transistor operation

force – voltage/currentwater flow – current - amplification

Transistor biasing The base-emitter (BE) junction is forward

biasedThe base-collector (BC) junction is reverse

biased.

IE=IB+IC

Operating regions of BJT

Cut off region

Linear region

Saturation region

Types of transistor

BJT - Bipolar Junction Transistor

UJT- Unipolar Junction Transistor

FET - Field Effect Transistor

MOS - Metal Oxide Semiconductor

Transistor applicationsTransistor as a switch

When used as an electronic switch, the transistor is normally operated alternately in cut-off and saturation regions.

Transistor as amplifierDue to the small changes in

base current the collector current will mimic the input with greater amplitude

Future of TransistorsMolecular electronicsCarbon nanotube transistorsNano inspiration wire transistorsQuantum computingCMOS devices will add functionality to CMOS

non-volatile memory, opto-electronics, sensing….CMOS technology will address new markets

macroelectronics, bio-medical devices, …Biology may provide for new technologies

bottom-up assembly, human intelligence

What’s new in transistor technology?3D Transistor made using Tri-Gate transistors on its 22nm logic technology.

Advantage of Tri-Gate Transistors ·More than 50% power reduction at

constant performance. ·37% performance increase at low voltage ·Improved performance and efficiency.