opamp simulation help

[windknows]

did you try setting Vdc to half the supply instand of zero?

the feedback will force the output to follow the input, so if you set the input to zero, the output will also be closed to zero volt, and since this cascode only have limited output swing, the nmos in the cascode won't work anymore..

 

[simon0123]

if I set the VDC = 1.65V, the nmos will work??

 

[windknows]

i think it should work, or maybe you can set it to the voltage of the net57. if it still not work, then maybe you should check the bias for these transistors

 

[simon0123]

after I set the VDC = 1.65 I see the gain is about 83dB. The following is the result, is it correct?

 

[windknows]

yes, i think so