noanob
Newbie level 4
I want to design a two stage Op amp .
There is some trade of for the gm of the first stage , you want high gm1 but gm1 can not be too high .
I did some homework for 0.35um CMOS tech with certain spec , now I want to re do it in 0.18um CMOS tech , but I don't have any spec . So I think I can start from 10uA tail current for the first stage .
The question is what is the maximum gain I can obtain for the first stage ?
Av = gm1*(Rout_n//Rout_p)
What is the maximum gm?
It seems with 5uA current for each branch , gm1 = sqrt(2Kn*W/L*Id) , but the simulations results is not like this . When I increase W/L , gm1 does not change linearly .
Thanks
There is some trade of for the gm of the first stage , you want high gm1 but gm1 can not be too high .
I did some homework for 0.35um CMOS tech with certain spec , now I want to re do it in 0.18um CMOS tech , but I don't have any spec . So I think I can start from 10uA tail current for the first stage .
The question is what is the maximum gain I can obtain for the first stage ?
Av = gm1*(Rout_n//Rout_p)
What is the maximum gm?
It seems with 5uA current for each branch , gm1 = sqrt(2Kn*W/L*Id) , but the simulations results is not like this . When I increase W/L , gm1 does not change linearly .
Thanks