hspice wrong calculations?

[jutek]

hello

I came across one problem during .OP simulation. I am simulating an opamp.

The thing is: i polarize PMOS gate by 0.8V . Source voltage is 1.2274
so Vgs=-0.4724 but in the output file Vgs is calculated as Vgs=-0.4273

What does this different come from?

regards

Luke

 

[qslazio]

i think you should check your model with NRD or NRS parameter value, because they stand for the source resistor and drain resistor which will result in small IR drop as you describe.