[PCB_FORUM] Re: 15.2 differential pairs and spacing setup

 Diane   See below in RED. 
I just set up a small board with these rules and it worked fine.
Did you forget the Assignment Table? Let me know how you make out.
Good luck

Paul Keefe
email paul_keefe@xxxxxxx




Dickoff, Diane J 
Sent by: 
01/25/2005 07:23 PM
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[PCB_FORUM] Re: 15.2 differential pairs and spacing setup






Paul---thanks for getting back to me. But I am getting DRCâs when I tried 
to use the net spacing type with my diff pairs.
I have 7mil gap and 5 mil width in my diff pair (from CM). I have several 
of these that need 20 mil spacing between these diff pairs. 
The DRC on the diff pair says I have 7 mil spacing and the net_spacing 
requires 20.
 
Thanks, Diane.
 

From: Paul_Keefe@xxxxxxx [mailto:Paul_Keefe@xxxxxxx] 
Sent: Tuesday, January 25, 2005 7:49 AM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] Re: 15.2 differential pairs and spacing setup
 

Yes Diane that will do it, we have these constraints all of the time and 
it works very well.  The Router 
will also do a very good job on them. 

  Good luck 

Paul Keefe




Dickoff, Diane J 
Sent by: 
01/24/2005 05:55 PM 


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[PCB_FORUM] 15.2 differential pairs and spacing setup
 


 
 




I know this has been discussed before but I want to make sure I am doing 
this correctly. 
  
I have a large number of differential pairs with different spacing within 
the diff pairs. But I also need different spacing between the sets of diff 
pairs. 
  
For example 
  
Diffa+ and Diffa- has 7 mil spacing  In CM Primary Gap = 7 mil  , Add a 
Net_Spacing_type = DIFFA ( line to line = 20 )
Diffb+ and Diffb- has 6 mil spacing  In CM Primary Gap = 6 mil  , Add a 
Net_Spacing_type = DIFFB ( line to line = 20 )
Diffc+ and Diffc- has 8 mil spacing  In CM Primary Gap = 8 mil  , Add a 
Net_Spacing_type = DIFFC ( line to line = 26 )

In the Assignment table when DIFFA is next to DIFFB use the DIFFA rules. ( 
20 mil )
In the Assignment table when DIFFA is next to DIFFC use the DIFFC rules. ( 
26 mil )
In the Assignment table when DIFFA is next to DIFFA use the DIFFA rules. ( 
20 mil )
And so on till you have them all covered
  
Diffa(+/-) must have 20 mil spacing to Diffb(+/-) and 
It must have 26 mil spacing to Diffc(+/-) (for example) 
  
So in the CM, I can put the 7,6,8 mil spacing for the diff pairs. 
But do I still use the net_spacing_type for the 20 and 26 mil spacing? 
  
Thanks, Diane

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