About trouble with differential pairs after changing the inner layers weight
mulfycrowh , 06-30-2023, 01:01 PM
Hi everyone,
On the advice of my manufacturer, I have to change the weight of the inner layers from 1 oz to 1/2 oz.
The main goal is to get bigger widths for differential pairs.
I have no trouble with S50 tracks but AD doesn't trigger track width errors for the differential layers, whatever the layer.
All the rules are enabled.
Where could it come from?
Thanks.
On the advice of my manufacturer, I have to change the weight of the inner layers from 1 oz to 1/2 oz.
The main goal is to get bigger widths for differential pairs.
I have no trouble with S50 tracks but AD doesn't trigger track width errors for the differential layers, whatever the layer.
All the rules are enabled.
Where could it come from?
Thanks.
mulfycrowh , 06-30-2023, 01:28 PM
If we take the example for USB3, we have the following rule.
mulfycrowh , 06-30-2023, 01:31 PM
If I take a look in the design rules, we have (fourth line):
mulfycrowh , 06-30-2023, 01:33 PM
If I take a pair with a previous width of 0.223mm (identical gap = 0.127mm), it doesn't trigger any error.
Very weird!
Very weird!
mulfycrowh , 06-30-2023, 01:34 PM
I already rewrote the rule but it doesn't change anything.
qdrives , 06-30-2023, 02:08 PM
Is the rule enabled?
And possible in the right order?
Do you check for the rule?
Does Altium think that the rules apply (unary / binary)?
Right click (the track) -> "Applicable unary/binary rule..." and click the track (an possible a second object).
And possible in the right order?
Do you check for the rule?
Does Altium think that the rules apply (unary / binary)?
Right click (the track) -> "Applicable unary/binary rule..." and click the track (an possible a second object).
mulfycrowh , 06-30-2023, 03:01 PM
Each rule "DiffPairsRouting_..." is enabled.
The Design Rule checker says that everything is unchecked except Width that is checked for Batch.
If I put everything checked for Batch, it apparently runs but I don't have the green/yellow warning for the differential pairs, I get the info about the width being too small compared to the rule with the arrows.
The Design Rule checker says that everything is unchecked except Width that is checked for Batch.
If I put everything checked for Batch, it apparently runs but I don't have the green/yellow warning for the differential pairs, I get the info about the width being too small compared to the rule with the arrows.
mulfycrowh , 06-30-2023, 03:13 PM
My other projects have the configuration: everything online and batch for Width.
mulfycrowh , 06-30-2023, 03:45 PM
In fact the rules are here but the errors are not visible.
When, for example, I retrace a selected differential pair, it is changed accordingly to the rule.
When, for example, I retrace a selected differential pair, it is changed accordingly to the rule.
robertferanec , 07-01-2023, 01:00 AM
can you screenshot output after you run design rule check manually? are the rules listed there? is not violation limit number exceeding and error checking stopping?
mulfycrowh , 07-01-2023, 01:18 AM
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mulfycrowh , 07-01-2023, 12:34 PM
Something weird happened today.
I first of all fixed the single impedances without any trouble.
I noticed that 1 error remained at the end of the process: one pad of a component lost its DGND connection.
To solve the issue, I deleted the component and immediately noticed I got the errors on the differential pairs and all of them on each layer.
I reimported the schematics and place the component.
Everything was fine.
I ran a DRC and noticed that DRC makes the errors on differential pairs disappear.
The DRC reports no error on differential pair.
Any idea maybe?
I first of all fixed the single impedances without any trouble.
I noticed that 1 error remained at the end of the process: one pad of a component lost its DGND connection.
To solve the issue, I deleted the component and immediately noticed I got the errors on the differential pairs and all of them on each layer.
I reimported the schematics and place the component.
Everything was fine.
I ran a DRC and noticed that DRC makes the errors on differential pairs disappear.
The DRC reports no error on differential pair.
Any idea maybe?
mulfycrowh , 07-01-2023, 12:42 PM
Here attached the screenshot just after having reimported the component.
We clearly see the errors on differential pairs.
We clearly see the errors on differential pairs.
mulfycrowh , 07-01-2023, 12:48 PM
After replacing the component.
Everything looks fine.
Everything looks fine.
mulfycrowh , 07-01-2023, 12:52 PM
After running the DRC: all the errors on differential pairs are lost.
qdrives , 07-01-2023, 02:39 PM
If "batch" is not checked, that means the width is not checked when you start Tools / Design rule check... --> Run design rule check.
The screenshot I showed is Altium default and I do not do differential pairs.
For you I would see what the results is when you do check the Batch box for Differential pair routing.
For fixes: you could select all the nets (traces) and go to: Route / Retrace selected.
The screenshot I showed is Altium default and I do not do differential pairs.
For you I would see what the results is when you do check the Batch box for Differential pair routing.
For fixes: you could select all the nets (traces) and go to: Route / Retrace selected.
mulfycrowh , 07-01-2023, 04:34 PM
I think that if you select all the traces and Route > Retrace Selected, you take the chance that AD destroys the design on several locations.
What I do is I select only sections (2 or 3 segments) and often segments that are not contiguous.
It prevents AD to do weird things.
But it applies to single tracks and not to differential ones.
What I do is I select only sections (2 or 3 segments) and often segments that are not contiguous.
It prevents AD to do weird things.
But it applies to single tracks and not to differential ones.
qdrives , 07-02-2023, 01:13 PM
As per my other post:
In the Altium presentations it always seems to work. Retrace does not do what I expect.
In the Altium presentations it always seems to work. Retrace does not do what I expect.
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