How to get the coordinates of the extracted parasitics.

Document created by rick_sedlak on Oct 1, 2012
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How to determine the coordinates of parasitic resistors.

To get the coordinates on parasitic resistors in the parasitic extraction netlist from Calibre xRC

specify the RLOCATION keyword in the "PEX NETLIST" SVRF statement in your rulefile.


You can find the complete syntax for each netlist type in Chapter 4 of the SVRF manual on  Here is the syntax for the HSPICE format netlist choice:


     | SCHEMATICONLY [filename]}
     [CLOCATION]                    Note:  CLOCATION was introduced in v2012.2 release
     [COORDSCALE value]
     [GROUND ground_name]
     [PINNAMESEP character]
     [RLOCATION]                     Use this setting to get parasitic resistor coordinates
     [RSCALE value]
     [SEPARATOR sep_name]


Note that parasitic capacitors and resistors can be highlighted in RVE.


Individual parasitic resistors as well as capacitors can be selected and highlighted in RVE using:


    View > Net Parasitics


For more detail on this consult the Calibre Interactive and Calibre RVE User's Manual:


    Section:     Using Calibre RVE for PEX


In Calibre Interactive PEX you can request parasitic resistor coordinates in:

    Pex Options  >  Netlist  >  Format  >  Output R  >  Locations




How to determine the coordinates for parasitic coupling capacitors.

In Calibre 2012.2 and later releases you can request coordinates for parasitic capacitors with the CLOCATION keyword on the PEX NETLIST rule file statement.


Calibre Interactive PEX does not provide a means to request coordinates for parasitic capacitors as of the 2012.3 release.

Adding this feature to Calibre Interactive PEX is scheduled for a future release of the Calibre Interactive product.


You can use a netlist review method to determine them as follows:


If you have written an HSPICE netlist, for example, from an RCC extraction there will be three files:


    [1]  the top level netlist containing the intentional circuit,
    [2]  the .pex file containing one subckt per net: each subckt containing the RC tree structure modeling the net, and
    [3]  the .pxi file containing the instance calls to the net model subckts along with the coupling capacitors connecting between these net model instances.


To get the coordinates at the ends of the coupling capacitors:

turn on RLOCATION so the resistors have their coordinates cited in the net model subckts,

    In Calibre Interactive PEX     Pex Options  >  Netlist  >  Format  >  Output R  >  Locations

then either visually browse for both parasitic resistors or capacitors in RVE or trace through the netlist to find them.


To trace through the netlist to find coupling capacitor coordinates, start by identifying a specific coupling capacitor in the .pxi file, next trace its connections to the net model instances in the .pxi file, then determine on which pins to trace further into each net model subckt in the .pex file.  These net model subckt pins can then be traced in the .pex file into the body of the RC tree structure to get the coordinates of the R's to which the coupling caps ultimately connect.


Please Note:  Meaningful parasitic browsing and highlighting will not be possible if you have performed any form of parasitic reduction on the extracted information.


This is because the mapping from the physical shapes to the electrically equivalent reduced parasitic circuit is lost due to the reduction performed.