How to Design an Amplifier Using Given Gain

8/2/2019 How to Design an Amplifier Using Given Gain

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How to design an Amplifier using given Gain,

Input Impedance and output Impedance.

Introduction

Amplifier is the device which provides amplification.

Amplification is the increase the strength of a signal, the signal being of any type: voltage,

current or power of a circuit.

There are many forms of electronic circuits classed as amplifiers, from Operational

Amplifiers and Small Signal Amplifiers up to Large Signal and Power Amplifiers.

Amplifiers can be thought of as a simple box or block containing the amplifying device,

such as a Transistor, Field Effect Transistor or Op-amp, which has two input terminals and

two output terminals (ground being common) with the output signal being much greater than

that of the input signal as it has been "Amplified". An amplifiers performance is defined ashigh only if the amplified signal contains none or minimum number of distortions or

alterations when comparing with the original input signal. Amplifiers are of different types.

They are used in radios, television transmitters and receivers and even in most of the

electronic instruments. An ideal amplifier has three main properties, Input Resistance,

Output Resistance and of course amplification known commonly as Gain. No matter how

complicated an amplifier circuit is because a general amplifier model can be used to show

the relationship of those three properties.

Learning by Doing

Lets take this as an example to design a transistor amplifier which achieves these three basic

How to design an Amplifier using given Gain & Impedances 1


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requirements.

Gain of 50

Input impedance of 10k

Output impedance of 10

Introduction







such as a Transistor, Field Effect Transistor or Op-amp, which has two input terminals andtwo output terminals (ground being common) with the output signal being much greater than

that of the input signal as it has been "Amplified". An amplifiers performance is defined as

high only if the amplified signal contains none or minimum number of distortions or

alterations when comparing with the original input signal. Amplifiers are of different types.

They are used in radios, television transmitters and receivers and even in most of the





Learning by Doing


requirements.

Gain of 50





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Selecting A transistor

In a example like this, we have to follow given parameters and when we make assumptions

we have to mention them clearly in order to get better results. In an example like this,

We hope to use BC107, in separated biasing methods. The first transistor is in voltage-

divider bias and the second one is in emitter follower bias.Because we cant get all three

parameters in a single transistor bias.

From the data sheet of BC107, we can get the Input impedance and Gain of transistor, and

also we can get VBE

value as 0.7v.



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Introduction







such as a Transistor, Field Effect Transistor or Op-amp, which has two input terminals and

two output terminals (ground being common) with the output signal being much greater than

that of the input signal as it has been "Amplified". An amplifiers performance is defined as

high only if the amplified signal contains none or minimum number of distortions or

alterations when comparing with the original input signal. Amplifiers are of different types. They are used in radios, television transmitters and receivers and even in most of the





Learning by Doing


requirements.

Gain of 50



http://www.google.com/url?ct=abg&q=https://www.google.com/adsense/support/bin/request.py?contact=abg_afc&url=http://lakshanhere.hubpages.com/hub/How-to-design-a-Amplifier-using-given-Gain-Input-Imphedance-and-output-imphedance&hl=en&client=ca-pub-6958755572607374&adU=www.google.com/chrome&adT=ImageAd&gl=BR&usg=AFQjCNHMkY6Hh7nZ1fxWt5-DCup8RgMEPwhttp://www.google.com/url?ct=abg&q=https://www.google.com/adsense/support/bin/request.py?contact=abg_afc&url=http://lakshanhere.hubpages.com/hub/How-to-design-a-Amplifier-using-given-Gain-Input-Imphedance-and-output-imphedance&hl=en&client=ca-pub-6958755572607374&adU=www.google.com/chrome&adT=ImageAd&gl=BR&usg=AFQjCNHMkY6Hh7nZ1fxWt5-DCup8RgMEPw


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Source: Data sheet

Selecting A transistor

In a example like this, we have to follow given parameters and when we make assumptions

we have to mention them clearly in order to get better results. In an example like this,

We hope to use BC107, in separated biasing methods. The first transistor is in voltage-

divider bias and the second one is in emitter follower bias.Because we cant get all three

parameters in a single transistor bias.

From the data sheet of BC107, we can get the Input impedance and Gain of transistor, and

also we can get VBE

value as 0.7v.



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We used the first transistor to match the input impedance which is 10k and to give the needed

gain to the amplifier. The emitter follower is used here as its gain is 1 and this gain will not affectthe overall gain of the circuit. The second transistor used to get the needed output impedance. By



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this addition the overall gain of the amplifier can be reduced in small values. But according to our

mathematical calculations we can prove that given parameters are already achieved.

Hope this article would be useful for anyone who is interested in electronics specially for the

students.

http://lakshanhere.hubpages.com/hub/How-to-design-a-Amplifier-using-given-Gain-Input-

Imphedance-and-output-imphedance


How to Design an Amplifier Using Given Gain

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