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Applications of the different Class A transistor amplifier biasing conditions

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boyddex

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Hello,

I have a question on an electronic assignment that i cant seem to find an answer to, the assignments on Class A transistor amplifiers.

"List an application of the different biasing conditions of amplifiers?"

Ive search online and in books but cant seem to find examples, any help would be appreciated.

Thanks

Chris.
 
Didn't you know that a class-A power amplifier produces an awful lot of heat? Its heat wastes a lot of electricity even when the amplifier is just sitting there doing nothing. It can heat your entire neighbourhood in winter.

A class-AB power amplifier is common and inexpensive. Good ones sound perfect.

Some new power amplifiers are class-D (switching) for very low heating. Some are pretty good.

Some radio-frequency amplifiers are class-C. Their output is tuned so the severe distortion is reduced.
 
If by amplifier you mean a small signal amp and not a power amp then Class A is often used for such low level amplification. They can be used for audio through RF frequency amplification.
 
Thanks for the reply's

I know there efficiency is around 20%, and theres better options :D

My concern is that the previous question in the assignment asks about current bias and voltage divider bias, both result in effectively a different circuit design.

Would RF and Audio amplifiers use current bias alone or voltage divider bias to remove the need to re-bias the amplifier if the transistor failed?

Thanks again

Chris.
 
Found it :D

Current Bias
pH Electrode Amplifier

Voltage Divider Bias
Guitar Phono (Audio) Pre-amplifier

Thanks again for the help.

Chris.
 
About the class A, never forget that while it is power inneficient, it is one of the cleanest amp you can get in term of signal. The SNR (or any other way of measuring noise) of these amp is pretty good. However, yes you may also heat your whole house with it. For 99% of applications it is deprecated, but it is still one of the best in term of initial learning.
 
The class of an amplifier has nothing to do with noise. Noise is rumble, hum and hiss.

Many class-A amplifiers have even-harmonics distortion.
Some class-AB amplifiers are excellent because they have very low distortion and are fairly efficient.
Ssome new class-D switching amplifiers are excellent and have very good efficiency.
 
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