Stats

  • State Suggested Answer
  • Replies 7
  • Answers 1
  • Subscribers 161
  • Views 2303
  • Members are here 0
More Content

Match Track Lengths Across Multiple Layers

PS202410214615

Hi everyone,

I’m working with Allegro X Editor 2023 and need help matching the track lengths for a few nets. These nets span across three different layers, and simply matching the total track length is not sufficient. I want to ensure that the signal timing is controlled across all layers, so I need to match the track length on each layer individually.

I've tried using the "Total Length" and "Relative Propagation Delay Length" features, but these methods are not giving the desired results, as they take the entire length into account rather than each individual layer.

Can anyone guide me on how to achieve this?

  • 0 in reply to JCTEYSSIER0

    I believe an SI simulation giving you an eye diagram will help.

    A significant change in impedance along any portion of the net will cause both changes in propagation speed and result in signal reflections.  I.E. your signal transition will get there in time but the logic/voltage levels won't work. 

    I believe the only cause for propagation to be noticeably different between signal layers is stackup config related.  

  • 0

    Hi !

    you can refer this code.

    ;+++++++++++++++++++++++++++++++++++++++++++++++++++++++++
    view = nil
    axlCmdRegister("total_length_net" `total_length_net)
    (defun total_length_net ()
    axlClearSelSet()
    axlSetFindFilter(?enabled '(noall NETS) ?onButtons '(noall ALL))
    mypopup = axlUIPopupDefine(nil (list (list "Done" 'axlFinishEnterFun) (list "Cancel" 'axlCancelEnterFun)))
    axlUIPopupSet( mypopup)
    while(axlSelect(?prompt "Please select an element...")
    STT =0
    if(view != nil then axlUIWClose(view))
    Input_List = axlGetSelSet()
    axlClearSelSet()
    Out_File = outfile("./total_length_net.log" "w")
    foreach(net Input_List
    pins = axlPinsOfNet(net 'pin)
    STT++
    if(length(pins) == 2 then
    parent = car(pins)->parent
    fprintf(Out_File "%-5d %s.%s %s.%s %-10s\n" STT parent->refdes car(pins)->number parent->refdes cadr(pins)->number net->name)
    path = axlFindPath(car(pins) cadr(pins))
    foreach(item path
    if(item->objType == "path" then
    fprintf(Out_File "\t%-10s %-10.2f\n" cadr(parseString(item->layer "/")) axlDBGetLength(item))
    )

    )

    )
    )
    close(Out_File)
    printf("Total: %n Found\n" STT)
    view= axlUIViewFileCreate("total_length_net.log", " " nil)
    )
    )

    Best Regards.

    HoangKhoi .

Cadence Guidelines

Community Guidelines

The Cadence Design Communities support Cadence users and technologists interacting to exchange ideas, news, technical information, and best practices to solve problems and get the most from Cadence technology. The community is open to everyone, and to provide the most value, we require participants to follow our Community Guidelines that facilitate a quality exchange of ideas and information. By accessing, contributing, using or downloading any materials from the site, you agree to be bound by the full Community Guidelines.