amplifier

[zxcv2201]

While reading Rajavi's book, I became curious as to why the following circuits were used.

If you know the purpose of the circuit please let me know

I know the purpose of (a) and (c).

thank you

 

[KlausST]

Hi,

I guess it´s a bit vague question ... and missing context.

So, when you show 5 circuits named a to e .. I guess they were from a document. Maybe the document gives some context.
Maybe it´s a test for an electronics class, then please refer to the manuscript of the class.

***
In short:
Each of these circuits has benefits and drawbacks.
* Some ar inverting, some not
* some are more for voltage amplification, others for current amplification
* some are more useful for higher frequencies some not
noise, gain, supply voltage, capacitances, supply current,

Why are there so many different brand and types of vehicles? Good thing there are! So every one can choose the right one for his requirements.... and taste.

It´s not a question that can be answered in detail within a couple of posts.
Maybe one can discuss 50 posts in this thread and still don´t have touched every detail.
Thus I think it´s the better way to look for tutorials (even videos. Many sources of both in the internet) or go to school to learn.

It´s much easier to do it the other way round: Give your requirements ... and one can recommend which circuit to use.

Klaus

 

[BradtheRad]

Circuit B lacks an emitter resistor which implies it's intended to give high gain. Rf has two functions: a) to apply bias, b) and as a feedback resistor because it discourages thermal runaway (if mosfet conducts too much then it pulls Rf low and reduces bias to mosfet).