Wow, thanks Jony.

Can you tell me what software to solve these equations?

 

I use Mathematica 7

 

I use Mathematica 7

Jony, is it free? Can you share me?

 

No I cannot do that. But you can check Maxima is a free software.

 

anhnha,

some other symbolic simulation programs are available for free:
* SNAP (from a Czech university)
* SAPWIN (from Uni Firenze,Italy).

Both accept controlled voltage and current sources. Very versatile.

 

Jony, is this the software you said?
http://www.wolfram.com/mathematica/

But you can check Maxima is a free software.

Does it have similar functions as yours?

 

anhnha,

some other symbolic simulation programs are available for free:
* SNAP (from a Czech university)
* SAPWIN (from Uni Firenze,Italy).

Both accept controlled voltage and current sources. Very versatile.

Thanks, could you confirm if these are what you meant?

1. http://snap.webpark.cz/indexa.html
2. http://sapwin.software.informer.com/3.0/

 

Yes - correct.
Hint: Both programs allow (of course) calculation and display of transfer functions as well as pole/zero distrribution (as numbers or as a diagram).

 

I use snap to check if my results are good.
And in snap I get exactly the same result as I show in post 20.
And I also find another program which is able to show symbolic solution.
http://www.physicsbox.com/indexsolveelec2en.html

 

Jony, which one did you use, snap or snapwin? I installed both of them but still can't figure out how to use.

 

I use this one
http://snap.webpark.cz/indexa.html
And read this
http://snap.webpark.cz/getting_started.pdf

 

Thanks, I will try it now.
BTW, is Mathematica software important and do you use it a lot?

 

Mathematica is a very good and powerful math software, and I use it a lot. But some time I use HP49+ calculator.

 

Regarding SNAP:
* Start with editor.exe
* Define the circuit (or load an example)
* Choose "Analysis" at the top of the window
* Click "snap" (this calls the snap simulation program)

 

Regarding SNAP:
* Start with editor.exe
* Define the circuit (or load an example)
* Choose "Analysis" at the top of the window
* Click "snap" (this calls the snap simulation program)

Thanks, I am reading manual and practicing now.

 

I think that I know how to find Rin for common gate stage.
All we need is to short Vin and connect our test voltage between M2 source and gnd.
Rin = Vtest/Itest

 

Incredible!
Finally I got the same result as yours in snap, Jony.
This software saved me a lot of time.

 

Here is my result:

Voltage gain, Kv:

Current gain:

Power gain: Kp = Kv*Ki

I want to maximize power gain and therefore I am thinking about removing Rs and minimizing R1 and R2.

What is the limit for R1, R2?

 

IF R1 and R2 >> Rd and RS the voltage gain is equal to
Kv ≈ Rd/(1/gm1 + RS)

 

IF R1 and R2 >> Rd and RS the voltage gain is equal to
Kv ≈ Rd/(1/gm1 + RS)

Yes, I was mistaken. Is there an upper limit for R1 and R2?