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Creating Differential Pair Class

mg1

I want to specify design rules for specific sets of differential pairs (e.g. Ethernet). In the PCB Editor --> Design Rules --> Differential Pairs Routing there is an option to apply that rule to a "Diff Pair Class". But I can't create a differential pair class in the schematic. At least there is no obvious way... I tried adding a "ClassName" Parameter to the Differential Pair Directive, but this just creates a Net Class and you can't choose to apply a "differential pair routing" rule to a net class.

For now I use the "Differential Pairs Editor" in the PCB to create a rule for a specific set of differential pairs, but it's not ideal. There must by a way to specify that class in the schematic.

  • 0

    From the schematic editor use Home > Directives > Differential Pair and add to each of the nets that make up the pair. Name the nets identically and then add a suffix of _N and _P to the nets (eg. MyNet_P, MyNet_N). The naming is important otherwise the nets will not be paired up correctly. Once complete use Home > Project > Update PCB File to transfer to the PCB. I don't believe there is a way to specify a differential pair class name in the schematic.

  • 0 in reply to e14softwareuk

    Hi,

     

    Thanks for your answer, but it's sadly not what I'm looking for. Creating the differential pair is not the problem. As you can see from screenshot below, there is an option in the design rules dialog to apply a rule to a differential pair class, but I haven't found a way to create that class... I can only choose "All Differential Pairs", which is not at all what I'm trying to do.

     

    image

  • 0 in reply to mg1

    Hey mg1,

     

    I've actually ran into this problem as well, it looks like most of these features are nerfed in Circuitstudio, what I found I that I can make a custom netclass and individually add each of the pair, however this only defines the individual trace impedance and not the differential one. Don't know if this will help you or if you have made any other progress on this.

  • 0 in reply to realworldtonystark

    Hi,

     

    Sadly I did not find a simple / elegant solution for this problem. I designed a PCB with several USB and a Gbit Ethernet Interface and it would have been great to specify a class for those equivalent differential pairs.

    I ended up using the "Differential Pairs Editor" in the PCB Editor. After you specify your differential pairs, they will show up in the Differential Pairs Editor. From there you can use the "Rule Wizard" button and if you specify the same "Prefix" and "Differential Pair Routing Rule Name" (e.g. "ETH_DiffPairsRouting") for all pairs, they should end up in the same rule. So in the end I got a Design Rule by the name of "ETH_DiffPairsRouting". When you open your Design Rules, this rule will still be marked "Where the object matches" --> "All", but when you click on the rule category "Differential Pairs Routing" the rule will have a scope specified with all the differential pairs you chose earlier...

  • 0

    Unfortunately creation of differential pair classes is not supported even in the PCB editor. Here's a screenshot of the class dialog showing the types that are supported.

    image