I've been trying to do trace length matching in Altium from one node to multiple and cannot seem to figure it out. The solution I have now (picture below) is to have 3 net ties that break up the one node into 3 and then make sure both sides match. The problem with this solution is I still need to manually match the 3 traces coming from the PATTERN_B node. Additionally, I have another trace elsewhere which need to have the same length as all 3 of these, so finding the trace length is additionally difficult because of the net ties now.

Matched Traces

Ideally, I'm looking for a reasonably automated tool (like the already existing trace length tuning) that will allow me to go from the 1 pattern node to all 3 input pins. A better way of manually doing this would be less good, but still helpful.

I'm on Altium 17.1 right now but might move to 18 soon, so I'm open to solutions on either version.

  • \$\begingroup\$ Can you give a bit more explanation of the big picture here? It's a bit weird to have to connect from 3 pins of one chip to 1 pin of something else. How closely do you need to match these lengths? \$\endgroup\$ – The Photon Jun 15 '18 at 16:59
  • \$\begingroup\$ PATTERN_B is coming from a digital pattern generator and switching all 3 inputs simultaneously. Obviously, I'd like the lengths as close as possible to reduce the input skew at the pins of the device but I don't have a specific threshold. \$\endgroup\$ – M Barnard Jun 15 '18 at 18:04
  • \$\begingroup\$ "as close as possible" is not a specification. You need to figure out if this means "less than 1 millisecond" or "less than 1 picosecond" or something in between. \$\endgroup\$ – The Photon Jun 15 '18 at 18:05
  • \$\begingroup\$ I don't see how defining a specification is relevant in this case where I am simply asking if a tool exists. But, if you really feel its necessary let's say <50ps. \$\endgroup\$ – M Barnard Jun 15 '18 at 18:13
  • \$\begingroup\$ It's relevant because if the requirement is "less than 1 microsecond" then the answer is "You're wasting your time because that's 10's of meters of trace length". And if the requirement is "less than 1 picosecond" the answer is "You're wasting your time because the chip's input pins won't be that well matched". \$\endgroup\$ – The Photon Jun 15 '18 at 18:15

This probably isn't everything you're looking for, but if you assign your three nets to a net class, you can use the PCB palette to compare their lengths at a glance as you edit the tracks:

enter image description here

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