I am trying to create a equation to plot the eye diagram from the voltage node Vout

As I define the equation, it tells me that the "Tbit" is not defined!?

I wonder why because I have already defined it on the schematic in the 'Var" icon

Does anyone know?

 

Ah, that's because it's defined as an equation variable that's local to the schematic/design file, and cannot be seen by the output file. To do this, look for the "measurement equation." The measurement equation will actually be shared between both the schematic/design file and the simulation output file. It also allows for you to use that variable in optimizations as well. HOWEVER, to use the measurement equations, you might have to also define all of the equations that measurement equation uses as measurement equations as well (thankfully, the window to do that works in the same way that the standard equations are, if I recall correctly).

Edit: The last sentence may be incorrect; you may be able to use the local equation variables within a measurement equation, but I don't quite remember.

 

Ah, that's because it's defined as an equation variable that's local to the schematic/design file, and cannot be seen by the output file. To do this, look for the "measurement equation." The measurement equation will actually be shared between both the schematic/design file and the simulation output file. It also allows for you to use that variable in optimizations as well. HOWEVER, to use the measurement equations, you might have to also define all of the equations that measurement equation uses as measurement equations as well (thankfully, the window to do that works in the same way that the standard equations are, if I recall correctly).

Edit: The last sentence may be incorrect; you may be able to use the local equation variables within a measurement equation, but I don't quite remember.

Thank You!