Differential Signals in Cadence Allegro

Hello,

I try to route in Allegro Studio v15.1 some differential pairs. I found several information on the net but it seems that I do not find the correct menu entries. I guess that my version of Allegro is out of date.

Can you tell me:
- Is this version (v15.1) of Allegro able to handle differential Signals?
- Is there a (pictured) tutorial or something like that to generate such a differential pair?

Thanks in advance
Christian

you can assaign Diffrential pair from menue logic>assaign diff pair
then fron menue Setup>Electrical Constraint spreadsheet you can assigen constrain for your Diff pair that you defined previosly

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it is work ok in the 15.2 , 15.5 15.7 V of allegro

emamss said:

you can assaign Diffrential pair from menue logic>assaign diff pair
then fron menue Setup>Electrical Constraint spreadsheet you can assigen constrain for your Diff pair that you defined previosly

Click to expand...

In the logic menu I have only 3 entries:
- Identify DC nets...
- Assign RefDes
- Auto Rename Refdes...

I do not see anything aboud differential pairs in the menus. Are there different versions of allegro (with/without support for differential signals)?

emamss said:

it is work ok in the 15.2 , 15.5 15.7 V of allegro

Click to expand...

Am I correct, that you mean that you verified from version 15.2 on? Or do you have a document written, that in only works in the named versions?

Thanks
Christian

you can change the Editor from menue File>change Editor then select Allegro PCB Desigen 620
or Try to open your file with Allegro PCB SI 630

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the menue change fro editor to other

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dear Christian;
if you need newer vresion it is avilable and easy to install any help i am ready i have V16.5 and some V15.x

emamss said:

you can change the Editor from menue File>change Editor then select Allegro PCB Desigen 620
or Try to open your file with Allegro PCB SI 630

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the menue change fro editor to other

- - - Updated - - -

Click to expand...

Yes, by changing the editor to Allegro Performance changed the menus such that I found the diffenerential pair entries!

emamss said:

dear Christian;
if you need newer vresion it is avilable and easy to install any help i am ready i have V16.5 and some V15.x

Click to expand...

I think you mean revision, right? I would like to use newer revision, but I am not allowed to do so. I am working a a institute of a university and there exists a large database of "special" parts in a handmade library by the users here. This library contains several special modifications as our etching process is not too precise etc.
There is the newer version of Cadence around but we students are not allowed (and able) to modify the libbrary. As the library seems to be incompatible with the new version, one has to manually convert all parts of it to the new format. This will last longer than my thesis at the instutut will last. Soon there will be some people that try to mirgrate, but too late for me.
So I will have to use the old version.


Now I have on additional question:
If I have some differential pairs (say one for clock, two for data) and I want to match the length of all of them, how would I do that? Of course I can create the differential pairs and modify by hand such that the total etch length matches.
But I think there should be a better way, I think.

Does it work over a "match group"? Is there a quicker way than adding all signals one after the other?

Thanks
Christian

Hi Christain;

frist: the new version of allegro suppot old files; in my company many Version of allegro 16.5 ,16.3 ,16.1 ,15.7 , 15.5 we have common liberary on server that all user use it but when we need to add new component footprint we create it with older Version "15.5" therfor all user can use this footprint.

note: you can setup many version of Allegro in the Same PC in the same time.

second;
you can create Match Group contain the Clock and two net's of diffrinital signal.for example the match Group contain Clock,S+,S-

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it work ISA

Best Regardes;
Eslam

emamss said:

Hi Christain;

frist: the new version of allegro suppot old files; in my company many Version of allegro 16.5 ,16.3 ,16.1 ,15.7 , 15.5 we have common liberary on server that all user use it but when we need to add new component footprint we create it with older Version "15.5" therfor all user can use this footprint.

note: you can setup many version of Allegro in the Same PC in the same time.

Click to expand...

I will ask and look what is possible. Thanks so far.

emamss said:

second;
you can create Match Group contain the Clock and two net's of diffrinital signal.for example the match Group contain Clock,S+,S-

- - - Updated - - -

it work ISA

Best Regardes;
Eslam

Click to expand...

OK, I created the match group and activated the constraints. Now my question is: How to modify the length of the signals such that they match? Is there a function to create these meander like lines or something similar? Or will I have to it "by hand" and route the signal multiple times?

Especially the signals in the match group are a LVDS set of signals (needs differential, length matched pairs). If there is a function to match, please keep this in mind.

Thanks
Christian

PS: What is ISA? In such applications?