You can run PEX on cells, by making the cell the top cell in the LAYOUT PRIMARY statement.
Parasitic extraction is based on connectivity, though, so simply doing a layout window through the entire stack of layers in your GDS is probably a huge headache. I suppose it could work if first you flatten the design (that is, get rid of all design hierarchy), then very carefully draw the area to leave as many nets intact as possible, and then figure out which nets no longer have drivers and connect them in the SPICE.
Why do you want to run on an area instead of on nets or cells? If speed is the concern, you might try excluding input using xcells, or even restricting it to just the nets you care about.
Hope that helps-
Yes, the speed is my concern.
Thank you very much for your reply.
How to create xcell for calibre PEX ?
For example I want to exclude I10(and2x1_i) , I11(and2x1_i) and I16(sw002a_i) .
Please give me example .
The methods have changed slightly over the years, so I'll describe it at a high level, and point you to the manuals for your version for details. I am most familiar with xRC (the manual is xrc_user.pdf), but I am told xACT is more widely deployed these days (xact_user.pdf). You might also be interested in the tips in the section "Improving Run Time" in the "Integration and Troubleshooting" chapter -- xcells aren't the only speed-up.
First, you need an xcell file. The format is similar to an hcell file, but has more options. The options available in your version will be described in the manual in a section titled "Xcell List Format". (xRC's 2016.1 version is at https://supportnet.mentor.com/docs/201601106/docs/htmldocs/mgchelp.htm#context=xrc_user&id=95&tag=ide3fa103b-4964-48cb-8… )
You can supply the xcell to the run using one of three methods:
- In the Calibre Interactive - PEX GUI, enter the filename in the Inputs button > Hcells tab > PEX x-Cells file box.
- If you are running from the command line (batch mode), add it to the -pdb call with -xcell <filename> OR
- (alternative way for batch runs) add it to the SVRF file with the statement PEX XCELL -- check the SVRF manual (svrf_ur.pdf) for which of the three formats to use for your set up.
The xRC and xACT manuals do have some tips on how to choose the cells to best improve performance. The xRC 2016.1 section is
"Tips For Choosing Xcells for Full Hierarchical Extraction". It is in a section ("Hierarchy Control with Xcells", in the "Handling Input" chapter) that also describes how xcells and hcells interact, and some additional features like wildcards and setting the xcell to be a specific cell instance.
Thank you very much for your reply .
Your advise is very helpful .