The cells and subcells (symbols and others) of your design can be stored in your
actual directory or in subdirectories, which are called libraries , wherever you want. You can specify the names of the libraries wherein SPICECAD is looking for symbols and others in the 'options'-dialog. The libraries are called 'librarypath1' ... 'librarypath5' . These paths can be absolute or relative. You can change these names during editing. To update the edited design, executed 'reload' in the main menu.
For example, if you want to try utilizing 741 OPAMPS in a design, and you see that they are not fast enough, change the search path from ./opamp_741 to ./opamp_op42 . If both paths contain a file called opamp.scm and opamp.sym , the replacement will be very fast. But do not forget to execute 'reload' to tell SPICECAD that there has been made a change which requires reloading the design. Of course, SPICECAD could itself detect that a change has been made to the library properties. But, this reload operation is a very complex operation which might crash from time to time. So, before 'reloading', please save the design.
At netlisting time , SPICECAD includes model files ( they always look like 'modelfilename.m') into the netlist. SPICECAD searches for these files in the model paths. The model paths can be defined in the 'options'-dialog. The modelpaths are called 'modelpath1' ... 'modelpath3' . These paths can be absolute or relative.
It is possible to convert MOS model names during netlisting. This is of particular interest if you have piece-wise defined models which are valid only within a limited gate length range. Some simulators, like HSPICE and TITAN, have a built-in mechanism which selects the appropriate model if gate length ranges are given. Other modulators, like SPICE3, do not have such a meachnism.
SPICECAD will help you convert your model names automatically on the fly.
If you execute 'model conversion' from the simulation menu, a model conversion dialog box will pop up. There, you can enter gate length ranges and old as well as new MOS model names.