hi pls where is the error in that design

I think The usual polarity of the gate source must be with the - connectet to the gate and + to the groung.

I've checked your design and it works! (for example with vgs=-0.2V and vds=1.5V, Idrain=10.3mA).
Mazz

hi,for rope,i use negative gate source, for mazz,i simulate but when i drain any chart there is no items to chiose what i do!

Look at the zapped project made in ads2003A.
Mazz

ps.: if you're using a previous version, simply edit the sch.dsn and correct the "1 7.600" with "1 x.x00".