Bootstrap this amplifier ?

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cartman007

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HI everyone.

I received this question to do.
My first question is, Is this an normal Emitter follower circuit when the output is take from the Collector?



Also what do they mean if they say I have to bootstrap this Amplifier without giving me any values for the components?

I dont understand the question.

Thanks
 



1.) No - it is NOT an emitter follower (in this case, the output would be at the emitter node).
2.) Do you know the meaning of the "bootstrap" method? This is a specific circuit modification for increasing the input impedance of the amplifier.
 


I have been through the book a couple of times. Its "electronic devices 9th edition " But I can not find anything resembling that circuit.

@FvM
Yes I have seen a couple of Bootstrap circuits but I dont know how I am suppose to convert one to another?

I know that a cap would be feed back the output into the input and a resistor in applied just before the input signal but I can not see how I can convert it?
If I had some details on component values then sure I can keep currents etc the same.
 


Again my question: Do you know how bootstrap works?
Otherwise, you cannot design a corresponding circuit.
 

LvW said:
Again my question: Do you know how bootstrap works?
Otherwise, you cannot design a corresponding circuit.
Click to expand...

It is to make a high impedance input by giving some positive feedback.
 

cartman007 said:
It is to make a high impedance input by giving some positive feedback.
Click to expand...

OK - in principle, correct.
Can you draw a corresponding circuit modification?
What about gain requirements afer modification?
 

Ok soo some research that I have done before posting resulted in this circuit popping up allot.

This is the original Emitter Follower with bootstrapping applied.


And because of my circuit I thought something like



The formula for resistor 3 is.

R3, = R3b = R3/ ( 1 - Ao )

But I dont have any values so I have no idea with what they want me to do.
 

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The circuit is useless due to missing emitter resistor. A meaningful circuit is shown in the post #2 link.
 

What about the output?

Does it also go to the Collector leg instead of the emitter as it was?

Thanks
 

I see exactly my circuit accept with a Re and the output on the collector.

But why would they tell me to convert one from the other?
It just seems more and more like they want me to just draw an entirely different circuit ?

Thanks
 

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