newbie2019, are you still working on this?

 

newbie2019, are you still working on this?

Yes dude.

 

Where are you in the process? What are you trying to do now?

 

The last part of my study involves computing the ac voltages and currents for
the configuration with negative feedback. The feedback loop obviously
complicates things and I cannot figure it out.

 

Where are you in the process? What are you trying to do now?

I think that I have the dc analysis of the two-stage amplifier with and without negative feedback
figured out. I have created a new post with regard to the ac analysis of same.

Mod: Merged the two Threads.

 

Do you know any of a circuit/network analysis techniques?

no..please teach us

 

no..please teach us

https://www.allaboutcircuits.com/textbook/direct-current/chpt-10/what-is-network-analysis/

The last part of my study involves computing the ac voltages and currents for
the configuration with negative feedback.

Do you know any of a circuit/network analysis techniques?

Also, what is the point of doing all those analyze and find AOL and ACL. If now you want to solve the circuit with the negative feedback directly? Without involving the "feedback theory" (without AOL ACL and feedback factor)?

We use a feedback theory to get approximation result without the need for direct analysis of a whole circuit.

 

https://www.allaboutcircuits.com/textbook/direct-current/chpt-10/what-is-network-analysis/


Do you know any of a circuit/network analysis techniques?

Also, what is the point of doing all those analyze and find AOL and ACL. If now you want to solve the circuit with the negative feedback directly? Without involving the "feedback theory" (without AOL ACL and feedback factor)?

We use a feedback theory to get approximation result without the need for direct analysis of a whole circuit.

First I had the circuit with no feedback and I was able to analyze the ac current and voltages.

Now that I have the same circuit but with negative feedback, the ac currents and voltages are different.
If I didn't have LTSpice how would I predict these new currents and voltages?

 

jony130, I sent you a PM.

 

no..please teach us

You and newbie2019 are apparently using the same text book. Have you learned standard network analysis techniques, such as nodal, mesh, loop?

 

If I didn't have LTSpice how would I predict these new currents and voltages?

You have to analyze the whole circuit one more time from the beginning. And it will be a hardcore job to do if you want the symbolic solution.

Good luck with that.

 

You and newbie2019 are apparently using the same text book. Have you learned standard network analysis techniques, such as nodal, mesh, loop?

nope..don't have his textbook

https://forum.allaboutcircuits.com/threads/two-stage-bjt-amplifier-with-feedback.26710/
yeah learned little of them but did not learn you and Jony's advanced method or advanced members I agree

but think this your circuit, RFB is positive feedback...Emitter of Q2 is negative with respect to Vbe...RFB is reducing emitter voltage and therefore increasing Vbe

if not then guess need re-read my book

Edit : oh sorry, see you said it is positive feedback

 

First I had the circuit with no feedback and I was able to analyze the ac current and voltages.

Now that I have the same circuit but with negative feedback, the ac currents and voltages are different.
If I didn't have LTSpice how would I predict these new currents and voltages?

Are required to use some particular technique to analyze your circuit, such as with concepts like loop gain, factors like Av / (1 + (Av * β)), etc., or can you use any technique you choose?

 

Are required to use some particular technique to analyze your circuit, such as with concepts like loop gain, factors like Av / (1 + (Av * β)), etc., or can you use any technique you choose?

@newbie2019

will advice to choose your answer carefully
look this before answering
https://forum.allaboutcircuits.com/threads/two-stage-bjt-amplifier-with-feedback.26710/

 

Assuming that newbie2019 will be back here eventually, and that he can use any technique, my next question for him will be this: do you have access to any mathematical software that can do symbolic linear algebra such as Matlab, Mathcad, Mathematica, Maple, or Macsyma?

If that answer to that question is yes, then the next thing to do is to watch this video:

That will help to understand what is going on in this thread: https://forum.allaboutcircuits.com/threads/two-stage-bjt-amplifier-with-feedback.26710/