[SI-LIST] Re: package SSN model accuracy requirements

I am surprised no-one in this thread has mentioned Saber (previously
Analogy, now Synopsis) which has its own modelling language, not too
difficult to learn, conforms to Kirchoff, and has a library of generalised
models.  Some years ago I implemented an experimental model for a GaAs
MESFET in Saber.  Significantly, Saber has not been heavily marketed in
recent years - perhaps someone from Synopsis can tell us why?

Cheers
Geoff

-----Original Message-----
From: Chris Cheng [mailto:Chris.Cheng@xxxxxxxxxxxx] 
Sent: 24 March 2005 01:27
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: package SSN model accuracy requirements

Arpad,

I can give you an even simpler answer, ever since the existence of IBIS, it
can't model a simple problem like SSO. If you are a customer, would you
choose a method that may be error if it is done wrong but at least give you
a chance to predict the problem if it is done right, or, something just
can't do the analysis AT ALL ? There are many road accidents with cars, but
that doesn't mean you have to walk to work.

Let me repeat the question I've asked many many times, how many of the
member of the Si-list who are NOT just professional standards attendee or
EDA tool vendors and have real responsibility to design system are actually
using a standard IBIS model to analyze SSO today ? I rest my case.

Garbage in garbage out, no matter it is SPICE or IBIS. At the end, whoever
give the model out has the ultimate responsibility. But ever since the
existence of IBIS, it can't address the problem high performance design (SSO
and receiver performance to name a few). You and I know that behavioral
models can address those problems long time ago but look at how long since
the first known successful attempt (if you disagree with me on that
reference, ping me off-line) until the standard committee even catch up with
the idea. Seven years is a very long time, people can earn sabbatical out of
that. Am I supposed to wait for another sabbatical if I want to model my
equalizing receivers ? I've got problems on things I need to ship tomorrow. 

Let's take a closer look at AMS
Here are the claims :

a) It abstract your I/O to protect your IP Well, Gary's reference seems to
suggest every I/O design is as simple as a university paper so may be your
company have no problem handing out the I/O state machine design. Is that
true ?
On the same reference we are led to believe a SPICE level=1'ish model is
really a behavioral model, ok I dig it, but do you think your company
lawyers and design managers will buy that and freely handing it out without
encryption ?

Like I said before, it's like asking "Can you tell me the secret of your
company ?"
Ans : "I can't tell you in English, but I can tell you in Martians (just not
to offend my earthly friends :-D)" 
Is that really possible (besides the fact that there is no Martian)?

b) It is accurate and fast
I still haven't seen any mention of SSO or how AMS can handle power impact
on the I/O, may be SSO is no longer an important issue for GB serial ports ?
How does one handle such modulation by predriver and substrate feedback from
multiple power sources (core power for predriver, I/O power for main driver)
without resorting to those level=1'ish transistor model ? A marketing paper
like what Gary present can carefully craft the example to the advantage of
the simulator but in reality how many interconnect is one simple S-parameter
deck ? I would bet the real customer topology will more like a mix bag of
circuit elements different vendor provide such as chip package, transmission
line, terminators, discrets, connector models. How the speed of AMS will do
when it is overloaded with a lot more circuit elements like R,L,C,
transmission lines and S-parameters by different components ?
Let's focus more on this little problem like a receiver, if you have to use
the output of the receiver to predict a equalization how would you use your
behavioral models to predict that ? Just take a look at those typical crazy
FSB ringback, over-drive specs. Try a few case of real over drive and ring
back cases which depends on common, differential mode, operating point, over
drive, hysteretic etc and try construct a multi-dimensional equation/table
to describe it and let's see how fast you will get. Ask the friends we both
know and have already make pitches in this thread what do they think ? I am
a fair person, show me a real life case and data and I will be convinced.

c) It is standard and everyone support it I still couldn't figure out
whether AMS is VHDL-AMS or Verilog-AMS, which one we are talk about here ?
Can you tell me ?
Does everyone use the same encryption to protect your IP ? If every tool has
a different encryption, what kind of ZBB do you think you will get for ten
different kinds of encryptors from ten different vendors ?



-----Original Message-----
From: Muranyi, Arpad [mailto:arpad.muranyi@xxxxxxxxx]
Sent: Wednesday, March 23, 2005 11:54 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: package SSN model accuracy requirements


Chris,

The same is also true for SPICE!  You are putting your faith into those
engineer's hands who write your process files.  And the average circuit
designer usually has no clue for how to correct a bad transistor process
file.  Many times they don't even know where the limitations of the model
are that they are using...

Having worked for the same company I work for, you should remember some of
the horror stories from those good old days when the IV curve of certain
transistor models were on the order of 2-3x away from measurements...  And
what did we do to get a quick fix?  We tweaked the .OPTIONS and did tricks
with other simulation parameters because the process files were not going to
change any time soon.  (Good luck doing this independently for the N and P
transistors).  But I think I may have already said too much, so I will stop
right here.

Arpad
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] =
On Behalf Of Chris Cheng
Sent: Wednesday, March 16, 2005 3:31 PM
Cc: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: package SSN model accuracy requirements


...
=20
d) Which brings back my fundamental problem with behavioral modelling. I
really don't know what the answers in c) should be but none of them = seems
straight forward enough to me that the Joe app engineer can crank out in =
the very near future. Anytime you have to attempt to deviate from the =
original design flow of the Si houses (which I presume is dominated by
SPICE), = you are putting faith in the app engineers who, up to now, can not
even = abstract out a standard to help me predict a simple SSO problem other
than using encrypted HSPICE.
=20
What do you think ?
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field

or to administer your membership from a web page, go to:
http://www.freelists.org/webpage/si-list

For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field

List FAQ wiki page is located at:
                http://si-list.org/wiki/wiki.pl?Si-List_FAQ

List technical documents are available at:
                http://www.si-list.org

List archives are viewable at:     
                http://www.freelists.org/archives/si-list
or at our remote archives:
                http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
                http://www.qsl.net/wb6tpu
  
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field

or to administer your membership from a web page, go to:
http://www.freelists.org/webpage/si-list

For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field

List FAQ wiki page is located at:
                http://si-list.org/wiki/wiki.pl?Si-List_FAQ

List technical documents are available at:
                http://www.si-list.org

List archives are viewable at:     
                http://www.freelists.org/archives/si-list
or at our remote archives:
                http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
                http://www.qsl.net/wb6tpu
  


_________________________________________________________

Zetex Semiconductors - Solutions for an analog world.

To read the latest news from Zetex, read our ZetexPress newsletter
online at www.zetex.com/zetexpress

http://www.zetex.com
_________________________________________________________

######################################################################
E-MAILS are susceptible to interference. You should not assume that
the contents originated from the sender or the Zetex Group or that they 
have been accurately reproduced from their original form.
Zetex accepts no responsibility for information, errors or omissions in
this e-mail nor for its use or misuse nor for any act committed or
omitted in connection with this communication.
If in doubt, please verify the authenticity with the sender.
######################################################################

------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field

or to administer your membership from a web page, go to:
http://www.freelists.org/webpage/si-list

For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field

List FAQ wiki page is located at:
                http://si-list.org/wiki/wiki.pl?Si-List_FAQ

List technical documents are available at:
                http://www.si-list.org

List archives are viewable at:     
                http://www.freelists.org/archives/si-list
or at our remote archives:
                http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
                http://www.qsl.net/wb6tpu

Other related posts: