What is the difference between LTspice XVII MOSFET and standard SPICE MOSFET models?
Besides the standard SPICE MOSFET models, LTspice XVII also includes a proprietary MOSFET model that is not implemented in other SPICE programs. It directly encapsulates the charge behavior of the vertical double diffused MOS transistor. This allows a power device to be modeled with an intrinsic VDMOS device LTspice instead of a subcircuit as in other SPICE programs. See the MOSFET section for details.
Can I add my own MOSFET models?
Yes, you can add your own model in the file %HOMEPATH%\Documents\LTspiceXVII\lib\cmp\standard.mos. This file is only for devices defined with a .model statement, not as subcircuits. If you want to use a subcircuit, follow the following steps:
Change the "Prefix" attribute of the component instance of the symbol to be an 'X'. Don't change the symbol, just the instances of the symbol as a component on a schematic. You can access this attribute by holding down the control key and right clicking on the body of the component.
Edit the "Value" attribute of the component to coincide with the name of the subcircuit you wish to use.
Add a SPICE directive on the schematic such as ".inc filename" where filename is the name of the file containing the definition of the subcircuit. Note that this must be the complete name with any file extension and Windows Explorer defaults to not showing the file extension. So you if you have a file called "mylib.sub.txt", which you can edit/view in notepad, and Windows Explorer shows you the file exists as "mylib.sub" The SPICE directive to include this file is ".inc mylib.sub.txt" If you used, ".inc mylib.sub" you will get an error message that that file can't be found.