Re: [SI-LIST] : length constraints in Specctraquest

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From: Lalit Shinde (lalit@cadence.com)
Date: Tue Sep 05 2000 - 08:01:57 PDT


Hi Aloke,

Here is how you can do it.
- Go to Constraint dialog box, Delay tab
- Select Driver, it's name appears as pin1
- Select Receiver, it's name appears as pin2.
- Change Rule Tpe from 'Delay' to 'Length'
- Enter min and max constraint values.
- Add the constraint rule.
  Note that it does not matter how many TLines/Traces
  are there between pin1 and pin2.
- Similarly go to Match-Delay tab and add constraint.
  Make the scope Global so that it applies to all
  bits of bus.

Now you can drive it back into Allegro/SPECCTRAQuest.
Note that you can also add these constraints in
Allegro/SPECCTRAQuest as well.

Aloke Bhattacharya wrote:
>
> Hello,
> I have a simple topology like this:
>
> Driver ------TL1---------/\/\/\/\-------TL2----------Receiver
> 33ohm
>
> The driver is connected to the receiver through a 33ohm series
> termination resistor. This Xnet is a part of
> a group of source synchronous signals and I need to apply the following
> constraints to the above topology in Sigxp:
> (i) the length of (TL1+TL2) has to match across all the signals within
> 50 mils.
> (ii)TL1+TL2 length should be between 1 inch and 6 inches
>
> In the set constraints menu of Sigxp, I don't see any option of applying
> delay or matched delay constraints
> to the sum of lengths of two or more transmission lines. Currently I am
> able to apply the delay or the matched delay constraint to only a single
> segment of a transmission line(like TL1 or TL2 in the above diagram).
> Does anybody know how to assign such a constraint in Sigxp? If it is not
> possible to assign it in Sigxp, is it possible to do it in Allegro?
>
> With regards,
> Aloke
>
> --
> **********************************************************************
> * Aloke Bhattacharya, *
> * Senior Engineer-VLSI/System Design,
> * *
> * Wipro Infotech, *
> * Global R&D, *
> * 88, M.G. Road, 5th Floor, *
> * S.B. Towers, *
> * Bangalore- 560 001 , *
> * INDIA *
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> * email: aloke.bhattacharya@wipro.com
> * *
> **********************************************************************
>
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-- 
Regards,
-Lalit.
978-262-6475.

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