[SI-LIST] Re: Simulation Question in Spectra Quest.

  • From: "Sivakumar S." <sivakumar@xxxxxxxxxxxxxxx>
  • To: heikod@xxxxxxxxxxx, si-list@xxxxxxxxxxxxx
  • Date: Wed, 15 Aug 2001 15:01:24 +0530

Hi SIexperts,
         I am doing Signal Integrity Analysis using Spectra Quest signal
explorer. I have a problem in simulating MPC8260 model. First i converted
MPC8260 IBIS model into ".dml" format using "ibis2signoise" utility and
there was an error message " TV curve should start at zero". I changed the
firtst line  of the rising and falling waveforms data "zero" and now there
was no error in the conversion and then i assigned this model to the device.
When i tried to do the simulation using this I/O model it gives "SERIOUS
Convergence Problem in Simulation of "DESIGN IO1 1" stimulus Pulse". 
         Can anybody help me to solve this problem?

Thanks and regards,
Sivakumar.S

-----Original Message-----
From: Heiko Dudek [mailto:heikod@xxxxxxxxxxx]
Sent: Thursday, August 09, 2001 3:31 PM
To: we_r_frendz@xxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Simulation Question in Spectra Quest.



Rahul,

 >1) The technology that I simulate makes use of
 >Differential strobes. Do I need to set up two strobes
 >in my simulation or a single strobe sampling at both
 >edges.

If your strobe line is layed out as a differential pair, you
definitely need to model this with a coupled trace element.
Same for driver / receiver (take care, often differential
drivers are used together with single receivers). You need
to use single or differential models, depending on what
you have in reality. No direct relation to sampling on
rising, falling or both edges. This again depends on
whatever technology you're simulating ... RAMBUS for
example samples on both edges. This way, a 400MHz
strobe results in 800MT/s.


 >2) Does the tool sample at both the edges or only at
 >the rising edges.

whatever you want it to. Select 'Set'->'Strobe Pins'. In
the 'Strobe Selection Window', you can set 'Active Edge'
to 'Both', 'Rising' or 'Falling'.


 >3)When we make use of Custom measurements, In the IO
 >cell Edit window there is a column for Freq. Does this
 >frequency indicate the sampling frequency ( The rate
 >at which the data is being sampled ). If so what does
 >the Clock freq that appears in the Analysis
 >preferences window indicate.

I assume you're talking about the I/O cell stimulus edit. You
do have the choice between different stimulus states ...
there's 'Rising', 'Falling', 'Pulse' and 'Custom' (and 'Quiet
hi', 'Quiet lo' and 'Tristate' as well). Whereas all I/O cells
with  rising, falling or pulse waveforms are operating in
sync and with whatever you set in the analysis preference
window as clock frequency. If you decide an I/O cell to
have a custom stimulus, you can set the clock frequency
to whatever you want and individually for all custom I/Os.
The frequency set in the analysis prefs has no influence
on custom I/O stimulus.


Hope this helps.

  - Heiko


Heiko Dudek
Technical Marketing Manager, High Speed Systems Design & IC Packaging
Cadence Design Systems, 270 Billerica Road, Chelmsford, MA 01824

ph (office Chelmsford, USA): (978) 262-6384
ph (office Feldkirchen, Germany): (089) 4563-0
fx (office Chelmsford, USA): (978) 446-6798
fx (office Feldkirchen, Germany): (089) 4563-1800
mobile world phone: USA - (617) 230 4233 or Europe - (+49) (172) 938 1541
email: heikod@xxxxxxxxxxx

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