connecting a wide wire net to gnd!/vdd!

Discussion in 'Cadence' started by Serkan, Jun 21, 2004.

  1. Serkan

    Serkan Guest

    I have to connect one bit of a bus (ie foo<7:0>) to ground, but if I
    directly connect it to a ground symbol it gives an error saying that
    net foo<0> is shorted to gnd!.. For simulation purposes I can use a 1
    ohm resistor, but now I have to draw the layout for the schematic, and
    that resistor gives a big headache.. What is the formal way to do the
    connection? (problem is merely at the schematic level, for the layout
    I can simply connect it by a Metal 1 path)..
     
    Serkan, Jun 21, 2004
    #1
  2. Serkan

    Alex G. Guest

    One possible solution is to connect each wire from bus to ground.
    That’s mean you should apply for example gnd<0:7>
    Another solution is to terminate it to a wire, instead of instance.
    Look "Understanding Connectivity and Naming Conventions" part of the
    "schematic composer user’s guide".
     
    Alex G., Jun 21, 2004
    #2
  3. If the bus is an internal net, you can use the "patch" component from analogLib,
    which creates aliases in the database.

    However, you cannot connect a pin to a global, or a global to a global, or a pin
    to a pin, using patch. If you need to do that, you can use "cds_thru" in basic,
    which will put a psuedo-short in - it needs some support in the verification
    tool (it netlists in CDL as a small value resistor, which Dracula and Assura can
    ignore if you set the *.RESI option in the netlist; in Diva you can add the
    removeDevice() command to your LVS rules to short it out). In other tools
    cds_thru is treated as either a current probe or a zero-voltage source, or a
    short (in Verilog). It also has the lxRemoveDevice property on it so that
    VirtuosoXL can treat it as a short too.

    Note, patch doesn't need to go to these lengths, because it implements an
    alias in the database which means that the nets are really shorted.

    Regards,

    Andrew.
     
    Andrew Beckett, Jun 22, 2004
    #3
  4. Serkan

    Serkan Guest

    Thank you very much.. "patch" sure solved my problem and thanks for
    the info on "cds_thru"..
    Regards,
    Serkan Ozdemir
     
    Serkan, Jun 22, 2004
    #4
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