Differential pair track width seems not to be respected

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1

I am struggling routing a differential pair (DP). What I would like is a certain track width for single-line routing (to move away from the footprint where the tracks start) and then the impedance adjusted settings for when the tracks are routed as DP.

My set-up in the netclass dialog is as follows:

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When there are absolutely no tracks connected to the net, then this works:

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However, when I have tracks with another width at either end, then the differential pair is routed with this width instead of the one set in the netclass setup.

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What am I doing wrongly here?

2

Does toggling the selection of this button change the behaviour?
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3

Yes, it does, thanks for pointing this out !

But then the next problem occurs: The width of the track stubs I connect to are changed when I finish the track:

Here is what I see while routing:

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When completing the track, everything connected is changed to the DP width:

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It seems I can work around this by locking the track stubs, but I think it would be good to have a way not to change the width of existing tracks when connecting to them.

4

Should this be set up in the design rules from the start based on the project requirements?