1-) Ri:100kohm
2-) Ro:1kohm
3-) output power: 15w
4-) gain: 60dB
5-) THD < %5
6-) Bandwidth: 100Hz-100KHz

(allowed parts: R, L, C, Bjt, Opamp, Power transistors as many as you want)

i know it is difficult. but it is my vital homework ever. ANY help, ANY clue will be appreciated. thank you.

 

which part should i start with....?
or, which property should i provide firstly?...

 

First you should start form pickup the right diagram.

 

First you should start form pickup the right diagram.

it looks too complicated for me, cant we realize that with more simple circuit ?

 

Well, yes if you allow to IC power opamp
For example this one
http://dac.ge/pdfs/23/3473.pdf

If not look here
http://sound.westhost.com/project76.htm

 

thanks for your help and interest. my teacher said about the homework that,
"it is easy, except 20w power at Ry it can be implemented with only 2-3 stage transisor.
to suply power, you should add some power transisors parallel to Ry"

and the matter is, i am not good at this lesson, and i cant do it on my own.

 

MY first diagram is 3 stage amplifier.
http://en.wikipedia.org/wiki/Electronic_amplifier

 

yes it is but still too complicated. at least for me.

 

the output impedance is desired <0.25ohm.. is it possible?

 

yes it is but still too complicated. at least for me.

So what type of a amplifier you are familiar with?

the output impedance is desired <0.25ohm.. is it possible?

Yes, if you use a large amount of a negative feedback

 

i can only understand from simple bjts. here is the project i am trying to complete.

 

Hmm, so maybe this diagram

 

well, what about the values ?

 

If you don't know how to calculate the values of the extremely simple power amplifier then you should repeat (fail) the course.

Whe did your extremely simple preamp have capacitors with a value of 10000000000uF?

 

If you don't know how to calculate the values of the extremely simple power amplifier then you should repeat (fail) the course.

Whe did your extremely simple preamp have capacitors with a value of 10000000000uF?

i just need to do this homework.

 

i managed to adjust gain and bandwidth on "Vp", but when i add power transisors, everything loses up. and gain falls to -50dB.. whats wrong

 

Well, Q4 is off (cut-of) all the time.
And Q3 has small current gain so he heavily loads Q5 amplifier.
And this is why voltage gain drop.

 

i had tried to add an ab class power amplifier behind Vp, but output dc voltage were supposed to be 10v (vcc/2), but it is not too. is it because r9 is too small? how can i make that power bjts work ?

 

Maybe becaues you forgot to add capacitor between output stage and R9.

And by the way, you need power supply voltage to be grater then
Vcc > 2 * √(2*Pout* Rload) = 25V

 

ok. i will add capacitor, there and then
as i understand, all i have to do is to change V2 for arranging power to 20w,