Subject: ibis-spice conversion in win98

From: 胡俊書 <[email-masked]>
Date: Wed, 5 May 1999 20:16:49 +0800

Dear All
	I have some questions about SDRAM IBIS model creation.
1. Can I use Hspice (DOS ver) and s2ibis2 (win95 ver) in win98 to make
ibis file?
2. Where can i find examples which close to SDRAM's *.s2i file, Because
i don't know how to write a *.s2i file correctly?
3. What's the relationship between *.sp, *.spi and *.s2i in the step of
making ibis? 
4. If i want to extract the ramp rate data of SDRAM (LVTTL), what kind
of input waveform  must be applied to
    the input node (perfect step function from 0-3.3v (3.3v-0) or
1ns/1ns rise/fall time waveform) ?
5. How to define the v_fixture of  LVTTL system and it will be added to
simulation the rising/falling waveform
     or not?

I need your help
thanks
Best Regards
Chris Hu

---

From: Scott McMorrow <[email-masked]>
Date: Wed, 05 May 1999 10:02:47 -0700

> 1. Can I use Hspice (DOS ver) and s2ibis2 (win95 ver) in win98 to make

Yes, as long as the batch file makes the correct dos command line
call to hspice.

>
> 2. Where can i find examples which close to SDRAM's *.s2i file,
> Because i don't know how to write a *.s2i file correctly?

There are examples in the s2ibis2 source code on the ibis web site.

>
>
> 3. What's the relationship between *.sp, *.spi and *.s2i in the step
> of making ibis?

.s2i is the s2ibis2 control file
.sp is your original spice file that has been modified by you to
     easily interface to the .s2i file spice calls.
.spi are the spice files that s2ibis2 creates to perform simulation
      these are created from the .s2i file and the .sp file, along with
      the .mod file
.mod contains the process information. This is often supplied by a
      manufacturer as a seperate set of process decks.  If there are not

      seperate decks, then you have to create files with calls to the
      appropriate library files.

> 1ns/1ns rise/fall time waveform) ?

In general, you can let s2ibis2 generate a default input ramp waveform,
since most models supplied by vendors are full transistor models, they
will perform some sort of wave shaping.

> 5. How to define the v_fixture of  LVTTL system and it will be added
> to simulation the rising/falling waveform
>      or not?
>

For standard totem pole outputs, four waveform tables need to be
generated, as follows:

Rising waveform, Vfixture = 0, Rfixture = nominal trace impedance
Rising waveform, Vfixture = Voh(max), Rfixture = nominal trace impedance

Falling waveform, Vfixture = 0, Rfixture = nominal trace impedance
Falling waveform, Vfixture = Voh(max), Rfixture = nominal trace
impedance

Voh(max) is usually the supply voltage.  As a result, you need to
also specify the Vfixture_min and Vfixture_max, which are consistant
with the voltages used to generate the IV curves.

Also, it is common for a device to drive multiple trace impedances on a
board,
or on multiple boards.  When this is the case, multiple sets of Rising
and
Falling waveforms must be created to cover the reasonable range of
transmission line impedances that a device will drive.  Multiples of 5
or 10
ohms are common. (i.e. 30,40,50,60,70,80 ohms)  For example, if the
nominal board trace impedance is 60 ohms and a driver is at the end of a

line, then it is driving a 60 ohm load.  However, if the driver is in
the middle
of a line, it is driving a 30 ohm load.  For the best simulation
accuracy, it
is best to have two sets of waveform tables to use, one generated at a
60 ohm load, and the other at a 30 ohm load.

Regards,

Scott