Hi, I would like to generate a PEX model including all the parasitic capacitances and resistances. I found two commands that can include parasitics: the first one are ext2spice cthresh 0 and _ext2spice rthresh 0_; the second one are extract do capacitance and extract do resistance. I am wondering which command (ext2spice or extract) is more accurate to include all parasitic capacitance and resistance. Thanks.

"rthresh" is a "lumped resistance" that is not really applicable to anything. The command you want is "extresist" with the "ext2spice extresist on" option. The resistance extraction is not known to work properly on hierarchy, so it is best to flatten a cell before you run extresist on it. Note that extraction in magic is a 2-step process. You will need to run both "extract" (which generates one or more .ext files) and "ext2spice" (which reads the .ext files and writes a .spice file). Generally, you will use "ext2spice" options to determine what parasitics (if any) you want in your final netlist. If you search this thread or #analog-design you should be able to find some posts on what commands to run for full R-C extraction using "extresist".

Sorry for the late reply. Thank you for the explanation!