Powerful Schematic Editor: CS offers a schematic editor that is easy to use and is highly efficient.Or, you can add the model to a symbol that you've built - which was the only way previously.Below we will discuss the main features of CircuitStudio in detail. From there you can directly place your model file onto the schematic as if it were a schematic symbol - a symbol is automatically generated when you do this. This is very similar to how you'd have multiple symbols in one library file. You can combine multiple models per file (I did it with *.lib models) - once combined into one file and installed into the library - you then can choose between different models from a single library file. Having to first add the spice file to the library and then adding that spice file to the symbol doesn't really make much sense. Prior to AD21 you could add the *.ckt file directly to the symbol - as you create the symbol in the library editor. The real issue with this method is that your components library will get cluttered very quickly.

After adding the *.ckt file to the library you then can add the *.ckt file to your symbol. First you install the *.ckt file to your component library - just you would for regular components (symbols and footprints). I was able to add a *.ckt file to a symbol - sort of. It would be nice to know how add a text-based spice file to a symbol in AD21 - if it's even possible now. But, it seems AD21 has changed and I sure as heck cannot figure out to add the simplest of SPICE models. All previous version of Altium Designer can import a *.ckt text file or add the text netlist directly to a symbol. So, I went to a much better tool (that's free) for my simulation needs.

I spent a coulpe of hours on this and gave up.

Altium designer spice simulation