Hi Guys,

I want to figure out the parasitic cap, res, and coupling cap between nets after extracting those parasitics using Calibre pex. It is disappointed for me to find that the annotated values are often unbelievable huge. The annotation is done with the following steps.

A calibre view is generated after running Calibre pex. Then I open the ADE in the schematic view, a Calibre pull down menu appears automatically in the Cadence schematic composer. Click Calibre -> Map Schematic Net... , a small window is poped up, named Map Schematic Nets to CalibreView Nets. In that window, click Select Schematic Net, then choose one net with the left key in the schematic view. Some resistor values are about 1000 Ω, some coupling caps are a few pico Farad, some parasitic caps between the net and the substrate are a few pico Farad, too. I think that they are too huge for the parasitics.

Is there any error in the operation to back-annotate the schematic? Any comments are appreciate.


Yawei

Dear Yawei,

                  I am also facing the same problem of pretty huge parasitic R and C in Calibre PEX netlist.
If you have found some clue already , please share.

hi all,
I don't know what version did you use and if this problem still confuse you.
In Calibre PEX v2008.1_20.15, you may extract specified net parasitic by your interest and you may shrink parasitic R and C by set the min R and min C (or min RC value).
To use this function:
Specify net: Output -> Netlist -> Specified Nets
Shrink R&C: Menu->Setup->PEX option->Netlist

Hope this is helpful.
Thanks,
Daniel Lai