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beamray , 04-15-2020, 11:32 AM

​Hey there, Guys!
I am doing pretty hard board with QDRII+ and manufacturer requires 10ps delay within bus and between buses. So I decided to try new AD20 feature -delay based length matching.
And I have 2 odd problems: xSignals just ignore echoclock traces, I do know why so lengh matching is not working on them. And second one delay based length matching is sending me confusing signals: traces are total different length and PCB panel says so, but tuning says they are Okay,
Any Ideas?

robertferanec , 04-16-2020, 08:11 AM

I do not even trust Altium's length matching (the length results are different between different altium versions). I am not planing to use delay feature in Altium to do length matching - seems to me too risky - at least for now.

But, I may be wrong ....

beamray , 04-16-2020, 11:20 AM

I am intrigued why on Earth AD is not seeing clock's traces on MOST layers. No DRC, TAB button selects trough net.... this is kind of darn magic.




I always double check with measuring primitives, but this board is complex, tiny, highspeed (JESD204B, 667Mhz QDR, DDR4 next to it, 6.6 Optics) and extremely mass-produced to-be. May be I will need Hyperlynx after all.... I would like to switch AD for something else, but company I am working in is forcing us.


I hope Somebody will help me with Xsignals issue.

robertferanec , 04-17-2020, 05:32 AM

- yeah, but if you go for delay length matching, the length may be different between signals and then measuring primitives may not be accurate. When using delay, some other factors may be considered e.g. length routed on top & bottom layers vs length in inner layers (difference in delay between these scenarious - however I do not know how far altium goes ... that is why I am not planning to use their delay feature yet).

beamray , 04-17-2020, 08:41 AM

Yep, That's why i always tunning each layer and try to make each inner signal layer same, specially highspeed ones.

I thought that AD should be doing good job, cuz they got integrated 3D field solver. buut ....
BTW 20.0.14 update done nothing with that.


ALSO! I have found one layer where xsignals catches traces (only new traces) for signals. but when I finish theme connection appear again.

beamray , 07-06-2020, 12:02 AM

BTW, ALTIUM 20.1.17 update fixed most of bugs.
But interactive tuning "Y"-key shortcut still not working.

Also Altium need to add within diff.pair phase shift auto (semi-auto) tunning, cuz it is still pain.(years past, but there is no way to do it other way than Robert shows in his course).

robertferanec , 07-06-2020, 08:52 AM

- yeah .. until they do not break it again

PS: Altium tries to improve interactive routing and tuning ... but I am not sure what exactly they do. It still doesn't work well for me - the suggested shape of track just keeps jumping around and it is suggesting the routing what is not what I am looking for (especially in places with many vias and limited space ...). Sometimes I think it is even worse then it used to be ...