[PCB_FORUM] Re: Propagation Rules driven from Schematic to Allegro

Hi Tony,

 

The DIFFP_PHASE_TOL value is treated as an absolute number so 25 mils
indicates that one net in the pair cannot be longer than 25 mils to the
other.

 

With RELATIVE_PROPAGATION_DELAY by leaving the Delta field blank will
give 25 mils absolute match and if the Delta field contains any other
number it will be treated as a +/- Tolerance. (Delta field is after the
S: in the example below)

            RELATIVE_PROPAGATION_DELAY GRP:G:L:S::25        -->  Means
the nets in the group should match to 25mils.

            RELATIVE_PROPAGATION_DELAY GRP:G:L:S:0:25      -->  Means
the nets in the group should match to +/-25mils which may yield up to 50
mils between nets.

 

I just wanted to clarify the Rel Prop Delay value settings.

Hope this helps,
Michael Catrambone
UTStarcom, Inc.

________________________________

From: icu-pcb-forum-bounce@xxxxxxxxxxxxx
[mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Cosentino, Tony
Sent: Friday, April 25, 2008 3:09 PM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] Re: Propagation Rules driven from Schematic to
Allegro

 

Just be careful because the 25 mil matching property may be +/-25 mils
not 25 mils absolute. I know with the REL_PROP_DELAY approach 25 mils is
really +/- which yields a total match length difference of 50 mils.

 

Thanks

Tony Cosentino

Tekelec

919-460-3656 office

919-414-2083 cell

 

________________________________

From: icu-pcb-forum-bounce@xxxxxxxxxxxxx
[mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Michael
Catrambone
Sent: Friday, April 25, 2008 3:15 PM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] Re: Propagation Rules driven from Schematic to
Allegro
Importance: High

You want to add a DIFFP_PHASE_TOL  <25 mil> to your diff pairs to
control the length between the pairs and not a Rel Prop Delay.  All of
the diff pair rules are easily controlled in Constraint manager and I
would recommend only passing the DIFFERENTIAL_PAIR property to define
your pairs and set everything else in Constraint Manager.

Hope this helps,
Michael Catrambone
UTStarcom, Inc.

________________________________

From: icu-pcb-forum-bounce@xxxxxxxxxxxxx
[mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Dale Rasmusen
Sent: Friday, April 25, 2008 1:55 PM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] Propagation Rules driven from Schematic to Allegro

 

Hi all, I was wondering how to do the following...  

 

I have diff pairs that need to have REL_PROP_DELAY GRP:G:L:S::25
properties between P and N signals.. but I also want to place 20 of
these pairs in a group that must adhere to a PROP_DELAY of
L:S:1000:2000.

 

Thus I have P and N constraints as well as a group prop delay
constraint.

 

I'm not sure how to structure these rules for Allegro.  Your help is
appreciated.

 

Thanks,

 

 

Dale Rasmusen

CAD Manager

TEKNOVUS

(707) 665-0400 ext 133

(707) 665-0491 fax

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