transistor. a transistor is a semiconductor device used to amplify and switch electronic signals...

15
TRANSISTOR

Upload: lorena-joseph

Post on 29-Dec-2015

264 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: TRANSISTOR.  A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power.  The transistor is the fundamental

TRANSISTOR

Page 2: TRANSISTOR.  A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power.  The transistor is the fundamental

A transistor is a semiconductor device used to

amplify and switch electronic signals and electrical

power.

The transistor is the fundamental building block of

modern electronic devices

There are two types of transistors

Bipolar Junction Transistor Field-effect Transistor

Page 3: TRANSISTOR.  A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power.  The transistor is the fundamental

Bipolar Junction Transistor

Bipolar junction transistor (BJTs) is made by three doped semiconductor region

separated by two pn junctions sown in figure 1.

The term bipolar refers to use both the holes and electrons as carriers in the

transistors structure.

There are two types of BJTs

npn (two n-regions separated by a p region)

pnp (two p-regions separated by a n region)

Page 4: TRANSISTOR.  A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power.  The transistor is the fundamental

Figure-1 Basic BJTs construction

Page 5: TRANSISTOR.  A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power.  The transistor is the fundamental

BASIC BJTs CONSTRUCTION

The pn-junction joining the base region and emitter region is called base

emitter junction

The pn-junction joining the base region and collector region is called base-

collector junction

A wire lead is connected to each of three region. These leads are labeled

E, B and C for emitter, base and collector respectively as shown in figure-1

(b).

The base region is highly doped as compare to heavily doped emitter and

moderately doped collector regions

Page 6: TRANSISTOR.  A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power.  The transistor is the fundamental

Figure-2 standard BJTs symbols

Page 7: TRANSISTOR.  A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power.  The transistor is the fundamental

BASIC BJTS OPERATION

Base- emitter junction is forward bias Base collector junction is reverse bias

Page 8: TRANSISTOR.  A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power.  The transistor is the fundamental

BJTs Currents and Voltages

Page 9: TRANSISTOR.  A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power.  The transistor is the fundamental

Voltage across RB is

By Ohms law

The value of IB is then

Page 10: TRANSISTOR.  A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power.  The transistor is the fundamental

Voltage at collector

Voltage across RC

Then the voltage at collector

The voltage at reverse bias collector base junction

Page 11: TRANSISTOR.  A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power.  The transistor is the fundamental

DC Beta(βDC)b

The ratio of collector current to base current is the current gain of transistors and is given by

Typical values of βDC ranges from 20 to 200.

Page 12: TRANSISTOR.  A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power.  The transistor is the fundamental

The ratio of collector current to emitter current is the dc αDC and is given by

The values of αDC range from 0.95- 0.99 but always less than 1.

Dc Alpha (αDC)

Page 13: TRANSISTOR.  A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power.  The transistor is the fundamental

Problem-1

Determine IB, IC , IE, VBE, VCE, and VCB in the following circuit (βDC = 150)

Page 14: TRANSISTOR.  A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power.  The transistor is the fundamental

Solution-1

Page 15: TRANSISTOR.  A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power.  The transistor is the fundamental

Problem-2

Determine IB, IC , IE, VBE, VCE, and VCB for the following circuit values (βDC = 90)

RC = 220 Ω

RB = 22 k Ω

VCC = 9V

VBB = 6V

Problem-3 Determine values of IE and βDC for a transistor whereIC = 3.65 mA IB = 50 µA