WORKING OF AN AMPLIFIER

GROUP MEMBER’S:

Zeeshan Shabbir

M. Bilal

Fiaz Ashraf

Talha Zameer

Umair Ali

Hammad Hassan

1. AMPLIFIER

2. PARTS OF AMPLIFIER

3. AMPLIFIER TYPES

4. OPERATIONAL AMPLIFIER

5. CLASSES OF AMPLIFIER

6. ADVANTAGES OF AMPLIFIER

7. USES OF AMPLIFIER

CONTENTS:

1. AMPLIFIER………………………………………………………Zeeshan Shabbir

2. PARTS OF AMPLIFIER…………………………………………..M. Bilal

3. AMPLIFIER TYPES……………………………………………...Fiaz Ashraf

4. OPERATIONAL AMPLIFIER……………………………………Talha Zameer

5. CLASSES OF AMPLIFIER…………………………………….…Umair Ali

6. ADVANTAGES OF AMPLIFIER…………………………………Hammad Hassan

7. USES OF AMPLIFIER……………………………………....................................

WORK DISTRIBUTION

AMPLIFIER BY:Zeeshan Shabbir

An  Amplifier  is an electronic device that increases the power of a signal. It does this by taking energy

from a power supply and controlling the output to match the input signal shape but with a

larger amplitude. In this sense, an amplifier modulates the output of the power supply. The output signal is

more than input signal.

AMPLIFIER:

The amplification process is similar to the way in which the human receives the sound from our

surrounding. Sound waves will be sent through a microphone. The diaphragm of the microphone moves it

in a peculiar motion and converts it into electrical signals. This fluctuating electric signal will be

represented as compressions and rarefactions of the original sound. The electric signal will be encoded by

the recorder and stored in a tape, CD and so on.

WORKING OF AMPLIFIER:

HOW AMPLIFIERS WORK:

Step 1:

In this setup the amplifier’s output circuit is connected to the emitter & the collector. The output circuit connects to the

emitter & the base.

Step 2:

When no current flow through the input circuit, free electrons from the n-type material fill the available holes in the p-type

material.

Step 3:

This create depletion zone (area where current can’t flow easily) at the boundaries b\w the n-type layers & the p-type layers.

Step 4:

When current flows across the input circuit, it cause an extra voltage boost at the base electrode. This gets electrons moving

again, shrinking the depletion zone. Electrical resistance drops & electrons can move from the emitter to the collector again.

In this way the voltage at the base electrode determines the overall resistance of the transistor & therefore the current in the

output signal.

PARTS OF AMPLIFIER BY:

M. Bilal

Transistor

Resistor

Diode

Parts Of Amplifier

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

It is composed of semiconductor material with at least three terminals for connection to an external circuit.

Transistor:

NPN Transistor: PNP Transistor:

A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit

element.

Resistor:

The most common function of a diode is to allow an electric current to pass in one direction (called the

diode's forward direction), while blocking current in the opposite direction (the reverse direction).

Diode

TYPES OF AMPLIFIER BY:

Fiaz Ashraf

The four basic types of amplifiers are as follows:

Voltage amplifier:

Current amplifier:

Transconductance amplifier:

Transresistance amplifier:

TYPES OF AMPLIFIER:

Voltage amplifier:

This is the most common type of amplifier. An input voltage is amplified to a larger output voltage. The

amplifier's input impedance is high and the output impedance is low.

TYPES OF AMPLIFIER:

Current amplifier:

This amplifier changes an input current to a larger output current. The amplifier's input impedance is low

and the output impedance is high.

TYPES OF AMPLIFIER:

Transconductance amplifier:

This amplifier responds to a changing input voltage by delivering a related changing output current.

TYPES OF AMPLIFIER:

Transresistance amplifier:

This amplifier responds to a changing input current by delivering a related changing output voltage. Other

names for the device are transimpedance amplifier and current-to-voltage converter.

TYPES OF AMPLIFIER:

OPERATIONAL AMPLIFIER BY:

Talha Zameer

Operational amplifiers can be used to perform mathematical operations on voltage signals such as

inversion, addition, subtraction, integration, differentiation, and multiplication by a constant.

Operational amplifier is used to amplify DC and AC signals.

OPERATIONAL AMPLIFIER:

Negative feedback

Negative Feedback is the process of "feeding back" a fraction of the output signal back to the input, but to

make the feedback negative, we must feed it back to the negative or "inverting input" terminal of the op-

amp using an external Feedback Resistor called Rƒ.

This feedback connection between the output and the inverting input terminal forces the differential input

voltage towards zero

This effect produces a closed loop circuit to the amplifier resulting in the gain of the amplifier now being

called its Closed-loop Gain.

BLOCK DIAGRAM OF OPERATIONAL AMPLIFIER:

+-

Gain (A) RL

Rs

Vs

Amplifier loadSource

VL

VL = A. Vs

Ideally the output voltage is amplified version of the source or

CLASSES OF AMPLIFIER BY:

Umair Ali

Amplifier Classes is the term used to differentiate between the different amplifier types.

The most commonly constructed amplifier classes are those that are used as audio amplifiers, mainly

class A, B, AB and C and to keep things simple, it is these types of amplifier classes we will look at here in

more detail.

CLASSES OF AMPLIFIER:

Class A

Class B

Class AB

Class C

CLASSES OF AMPLIFIER:

100% of the input signal is used (conduction angle Θ = 360°). The active element remains conducting all

of the time.

CLASS A:

50% of the input signal is used (Θ = 180°); the active element carries current half of each cycle, and is

turned off for the other half.

CLASS B:

As its name suggests, the Class AB Amplifier is a combination of the “Class A” and the “Class B” type

amplifiers

Class AB is intermediate between class A and B, the two active elements conduct more than half of the

time.

CLASS AB:

A class C amplifier conducts for less than 180.

Class C amplifiers are used extensively in radio communications

circuits.

CLASS C:

ADVANTAGES & USES OF AMPLIFIER BY:

Hammad Hassan

Despite the complexity involved, a properly designed class D amplifier offers the following benefits:

◦ Reduction in size and weight of the amplifier,

◦ Reduced power waste as heat dissipation and hence smaller (or no) heat sinks,

◦ Reduction in cost due to smaller heat sink and compact circuitry,

◦ Very high power conversion efficiency, usually above 90% above one quarter of the amplifier's

maximum power, and around 50% at low power levels.

ADVANTAGES OF AMPLIFIER:

Home Theatre systems:

USES OF AMPLIFIER:

Mobile phones: The internal loudspeaker is driven by up to 1 W.

USES OF AMPLIFIER:

Powered speakers: Powered speakers, also known as self-powered speakers and active speakers, are

loudspeakers that have built-in amplifiers.

USES OF AMPLIFIER:

High-end audio:

USES OF AMPLIFIER:

Bass amplifiers: Bass instrument amplification, used for the bass guitar, double bass and similar

instruments.

USES OF AMPLIFIER:

Sound Reinforcement: A sound reinforcement system is the combination of microphones, signal

processors, amplifiers, and loudspeakers that makes live or pre-recorded sounds louder and may also

distribute those sounds to a larger or more distant audience

USES OF AMPLIFIER:

Active subwoofers: A subwoofer (or sub) is a woofer, or a complete loudspeaker, which is dedicated to

the reproduction of low-pitched audio frequencies known as bass.

USES OF AMPLIFIER:

Any Q…..???