Plotting Output Impedance of an Inverter

There are a couple of ways I can think of.

First, you can just follow the definition of output impedance. Just place a voltage source at the output node and measure the current leaving the source. After that, it is just ohm's law (R = V/I). This will be the most relevant indication if you really only care about the output.

However, if you want to know the individual transistor ron and rop, cadence does calculate the rds of the transistors at the bias point you set. Just run a DC analysis in Analog Design Environment (ADE) with the save operating bias checkbox checked. Now run the simulation. If this was done correctly, you should now be able to click on Results>Annotate>DC Operating Points. Finally, go to the schematic and click on the transistor you are interested in. This would produce a pop-up window with information about the transistor bias state, which includes its rds value.

There are a couple of ways I can think of.

First, you can just follow the definition of output impedance. Just place a voltage source at the output node and measure the current leaving the source. After that, it is just ohm's law (R = V/I). This will be the most relevant indication if you really only care about the output.

However, if you want to know the individual transistor ron and rop, cadence does calculate the rds of the transistors at the bias point you set. Just run a DC analysis in Analog Design Environment (ADE) with the save operating bias checkbox checked. Now run the simulation. If this was done correctly, you should now be able to click on Results>Annotate>DC Operating Points. Finally, go to the schematic and click on the transistor you are interested in. This would produce a pop-up window with information about the transistor bias state, which includes its rds value.