how to calculate output res based on simulated op point?

[nus_lin]

dear guys,

how to calculate the output resistance based on the saved op point? i found that in spectre, the "ron" shown in the table of op point did not equal to gain/gm. it is so weired. how is this ron defined in bsim3v3 model?

 

[Vamsi Mocherla]

I think that you should be comparing to 1/gds and not ron, if you want the output resistance of your transistor. If it is a short channel transistor, there could still be more errors in the rds. But it will not be orders smaller. So, please look for gds in your spectre results.