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About xSignals

mulfycrowh , 02-10-2021, 12:35 PM
Hi everyone,

I would like to route as differential the paths TX_N, TX_P, RX_N and RX_P as shown on the attached screenshot.
U14 could be defined as the source, the connector (P2) as the destination.
As you can state, there are 4 series resistors.
I went to Design > xSignals > Create xSignals.
How should I proceed?
I tried many things.
Could you help please?





mulfycrowh , 02-10-2021, 01:10 PM
If I select P2 as source and R48, R50, R52, R54 as destinations in the wizard, AD detects all 4 differential signals.
But if I select P2 and U14, AD detects nothing.
goncaloc , 02-11-2021, 03:18 AM
The signals coming from U14 are not defined as differential signals, they should, as it is done on both TX and RX, end with _P and _N
robertferanec , 02-15-2021, 12:53 AM
@goncaloc nice spot! @mulfycrowh is it working after naming the nets correctly?
mulfycrowh , 02-16-2021, 02:22 PM
@robertferanec I thought that AD could automatically detect the series resistor within the differential pair. It is doable!
mulfycrowh , 02-16-2021, 02:23 PM
If I introduce another differential pair net, it is OK.
mulfycrowh , 02-16-2021, 02:30 PM
Now. I found that the suggested differential routing is not good as shown on the attached screenshot.
It is like like an automated routing.
Is there a way to go, in that case from the connector to the diode directly?
przemek , 02-17-2021, 02:07 AM
Hi,
you can adjust your traces after routing by sliding them. By the way, maybe rotate D9 by 180° to keep the nets close each other for as long as possible?
mulfycrowh , 02-17-2021, 04:10 PM
Here is the result of my differential routing.
It is very hard to keep the impedance on each point because of the size of the components.
Comments:
goncaloc, 02-18-2021, 01:44 AM
Looking good
mulfycrowh , 02-18-2021, 06:13 AM
@goncaloc What is the short key to disable snapping when routing differential pairs?
Thanks.
przemek , 02-18-2021, 07:31 AM
It should be Shift + E - switching between snaping to all layers/current layer/snapping off.
robertferanec , 02-18-2021, 10:52 AM
When routing, hold down CTRL
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