[SI-LIST] Re: About S2ibis2

  • From: "Lynne D. Green" <lgreen22@xxxxxxxxxxxxxx>
  • To: <cui_930@xxxxxxx>, <si-list@xxxxxxxxxxxxx>
  • Date: Mon, 27 Nov 2006 20:50:14 -0800

Hi, James,

First, you must decide how Vcc_core will vary with corners.  It might vary
in the same direction as Vcc_pu, or in the opposite direction, or not at
all.  SPICE can help you determine the best/worst case combinations
(corresponding to IBIS min/max corners).

The SPICE input files must have Vcc (Vcc_pu) set the normal way for
s2ibnis3.  The Vcc_core (1.8V) source must be created, with the desired
voltage,  before the SPICE files generated by s2ibis3 are simulated.  This
can not be done using the default s2ibis3 flow.

There are two ways to add a Vcc_core voltage source under s2ibis3.  One
could add the Vcc_core pin to the subckt AND to every call to the subckt,
and add a Vcc_core voltage source - this requires editing EVERY SPICE file
generated by s2ibis3, running SPICE, then running s2ibis3 model extraction.
Alternatively, one could add a Vcc_core voltage source within the subckt -
this has the advantage that one does not need to edit the s2ibis3 netlists,
except to set the voltage for Vcc_core.  I personally prefer the second
approach, but either one will work.

Best of luck,
Lynne

PS: Please check my web site for upcoming IBIS training classes.  We are
willing to arrange classes in additional locations.


"IBIS training when you need it, where you need it."

Dr. Lynne Green
Green Streak Programs
http://www.greenstreakprograms.com
425-788-0412
lgreen22@xxxxxxxxxxxxxx

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of james cui
Sent: Monday, November 27, 2006 7:47 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] About S2ibis2

Hello,ALL
thanks Lynne for your help
I have another question about S2IBIS2.


How can I change ".DC" sweep range to generate Pullup curve,but not change
core power?
(now)   **Pullup curve   Vcc=1.8v
            **core power   Vcc=1.8v
(I want)**Pullup curve   Vcc=3.3v
           **core power    Vcc=1.8v

Thanks


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