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Setting DC impedance for nets

Mysil B

We do quite a lot of designs where we use the trace resistance to balance diodes in parallel for DC currents. Is there any way we can set the a impedance constraint for this so we can control the lengths automatically? Since we vary the width on these traces and mix them with copper polygons, we cannot simply set a track length constraint... We'd need to have a constraint on total resistance from end to end on a single net.

Best regards, Mysil

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  • DavidJHutchins

    There are a couple of different ways of accessing a property such as that, first is the property definition:

    skill 'axlDBCreatePropDictEntry("net_resistance" "resistance" list("nets"))'

    below is a simple function that scans all the design for that property & prints it's name & value:

    procedure(net_res_test()
    foreach( net axlDBGetDesign()->nets
    when(net->prop->NET_RESISTANCE
    axlMsgPut("net %s NET_RESISTANCE %s" net->name net->prop->NET_RESISTANCE)
    )
    )
    )

    below is an example of running it:

    Command > skill net_res_test
    net PWRBRK_N_NC NET_RESISTANCE 0.123 Ohm
    (dbid:372454688 dbid:372454632 dbid:372454576 dbid:372454520 dbid:372454464 dbid:372454408 dbid:372454352 dbid:372454296 dbid:372454240 dbid:372454184 dbid:372343864 dbid:372343808 dbid:372343752
    )

  • Mysil B
    in reply to DavidJHutchins

    Thank you very much, David! I shall try it out. There is no way of autorouting nets using SKILL scripts?

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  • Mysil B
    in reply to DavidJHutchins

    Thank you very much, David! I shall try it out. There is no way of autorouting nets using SKILL scripts?

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