Hi All, I was trying to simulate my design in the SPICE with the spice directives for PMOS and NMOS models using the file "sky130_fd_pr__nfet_01v8_lvt". It is giving me the following error that says it can not find the definition of model "sky130_fd_pr__nfet_01v8_lvt_model" L=1 W=1. Where I have used the length and width of the NMOS as 1 (just for the purpose of testing). My questions are- ** Why are there 38 models all together in the library file? ** How do I choose which model is appropriate for my design so that it won't generate the error I am currently getting? ** This is how I am calling the model directive- • 'Ctrl + right click' on the nmos4. Component Attribute Editor opened I changed the prefix value to X and value to "sky130_fd_pr__nfet_01v8_lvt" which is after the .subckt statement in the model file. • I added the SPICE directive which I have copied from GitHub and named it nmos4.lib as .lib nmos4.lib ** Is the error generating because I am not specifying which model I am choosing out of the 38 models presented in the "sky130_fd_pr__nfet_01v8_lvt" file under the subckt called by the same name? I would appreciate any kind of help to solve this issue. TIA!!!!!

The models are different for different width and lengths. That's way there are so many. L=1 and W = 1 is very big. if you installed it with open pdk there is on automatic setting that scales everything with e-6. If not, trying again with some smaller values can help (not sure if that's the problem)

Hi Webers, Thanx for the explanation. I was thinking the same! I have one more question- Shall I use the .subckt statement to call the model definition or just a specific model under which my W/L will be satisfied? Because when I am calling the model definition with the .subckt statement it is giving me this error where it is basically saying that it can not find the model. I have also tried doing the .model statement specifying one of the models then it worked!!! I just want to make sure which models to use for my simulation!!! Is the model to chose should be the one which has the range within which my W/L is satisfied?