ron and rout in DC analysis

[anhnha]

In cadence DC analysis operating point there are two parameters ron and rout.
I see that ron and rout are defined for all operating region (sub-threshold, triode, saturation).
So, what are the definition or how these parameters are calculated in these regions?
It makes sense to define ron in triode region but I don't quite understand how should I understand ron in other regions.

 

[erikl]

... It makes sense to define ron in triode region but I don't quite understand how should I understand ron in other regions.

It's the same in saturation region: ron = δVds/δIds . Gives you a good feeling for the Early voltage, respectively for the output impedance e.g. of a current source|mirror.

BTW: subthreshold is not a region, but an operation mode.

 

[anhnha]

Thanks for the answer!
So, for example, in saturation what is the difference between Ron and Rout here?

 

[erikl]

... for example, in saturation what is the difference between Ron and Rout here?

Not only in saturation, in any region: Ron = 1/gds of the transistor alone, whereas Rout includes the resistance (in parallel) of all possible other devices in parallel, e.g. more parallel drivers, mostly only the load.