Re: [SI-LIST] : receiver jitter

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From: Jim Freeman (freeman@broadcom.com)
Date: Wed Jan 19 2000 - 12:00:35 PST


Hi Jonathon,
    I'm sure all system people on the list are perfectly willing to sign up to differential signalling for 128 bit data busses(NOT).

Jim Freeman

Jonathan Dowling wrote:

> I'll tell you what.....Let's make a deal !!
> In the spirit of Andy Rooney's offer of $1,000,000.00 to anyone who can identify Nicole's
> killer....
>
> In America, we vote with dollars. Instead of arguing, lets put it to such a vote.
>
> Given that Intel is the bellweather of the industry and given that the membership of the
> SI-LIST is dominated by Intel employees (as Ray can attest), the tool adoption trend
> seen there should more or less be reflected in the majority of the industry.
>
> I'm willing to concede the point when Intel can definitively report that it has less than
> 100 IBIS compatible simulator licenses. This means all XTK, ICX, SpecctraQuest
> licenses and other IBIS-like simulators. This includes those of you who use linear excitation for
> MDS/ADS and Speed97. Consider yourselves behaviorists. Those who use the behavioral
> modeling facility in Hspice should also be included.
>
> My best guess is that they have:
> 60-75 XTK
> 40-60 SpecctraQuest
> 5-10 ICX
> 25-50 Other
>
> If Intel does have more than 100 IBIS compatible simulator licenses, how does this square with
> "the death of IBIS" scenario?
>
> Argueably, the worst problem with behavioral simulators is that they do not (or poorly) predict
> switching noise. The trend to convert to differential signaling eliminates this problem by
> suppressing SSO by 20x. This should enable a renaissance in behavioral modeling and
> should increase its adoption rather than serve as a restriction.
>
> Interconnect researchers using Spice may want to find out who is bankrolling their research
> these days. It may not say so on your paycheck, but while you fight convergence problems, someone
> using a behavioral simulator is paying your bills through the design of real, timely products
> that make real money.
> Right Chris?
>
>
> Jonathan Dowling
>
> --- Chris Cheng <hycheng@3pardata.com> wrote:
> > hmmm.... interesting. i wonder who design gtl buses first ?
> > ahh.... its got to be mr. gunning cause its called gunning tranceiver
> > logic.
> > ohhh.... he designed it first with a company call what ?
> > so.... please check who published the first system/bus design paper
> > in the industry on gtl. i give u a hint, the first author's name starts
> > with a c. and i assure u he only used spice to design the first gtl
> > system with 10 slot loading at 66MHz without a dead cycle in the
> > days of 80486.
> > for the record, i defined the corp. cad signal intrigity methodology
> > in sun more than 10 years ago and for sure behavoral model was in
> > it but over time performance requirement and accuarcy concern has
> > shift everything to spice. yes, i am still using behavoral model
> > when i am designing pci or jtag but it stops there.
> > actually intel has boat loads of spice license too (its free since
> > its in house tool). so i don't understand your comment on 100's of
> > behavoral simulators.
> > chris
> >
> > -----Original Message-----
> > From: owner-si-list@silab.eng.sun.com
> > [mailto:owner-si-list@silab.eng.sun.com]On Behalf Of Jonathan Dowling
> > Sent: Tuesday, January 18, 2000 5:57 PM
> > To: si-list@silab.eng.sun.com
> > Subject: Re: [SI-LIST] : receiver jitter
> >
> >
> > Newbies: Time for a history lesson...
> >
> > I would be willing to bet Chris' sentiments today were issued
> > verbatim by critics of behavioral modeling at the folks who
> > developed behavioral simulators in the 1980's (or before).
> > Proponents of SPICE have long criticized IBIS-like simulators,
> > even when signal quality not an issue (only timing).
> >
> > If we go back in time we would hear:
> > "We are going to be running at 4MHz this year. You can't correctly
> > predict timing with a behavioral model. This is 5V logic. You will
> > have to use SPICE. Specifically, you can't model the receiver well
> > enough."
> >
> > The true test is time-to-market. Almost without exception, all
> > the companies that excel at time-to-market in the digital world
> > have boatloads of behavioral simulator licenses. Intel is the
> > best example of this fact because they make the most money.
> > Their behavioral simulator licenses number in the 100's. If you
> > claim your company excels at time-to-market without behavioral
> > simulation, I claim your company is not as successful as Intel.
> >
> > Rambus's SPICE bigotry certainly contributed to their poor
> > time-to-market showing last year. Maybe they don't have a single
> > behavioral simulator in-house. They were generous enough to make
> > an IBIS model, but it was pooh-poohed by the 'experts' who claimed
> > (on this reflector list) that only the SPICE model would do.
> > Simulation with the simple IBIS model is enough to show timing
> > marginality at 800MT/s. (By the way, it looks great at 600MT/s
> > if you're lucky enough to avoid the resonances.)
> >
> > Jonathan Dowling
> >
> >
> >
> >
> >
> > --- Chris Cheng <hycheng@3pardata.com> wrote:
> > > as core and signal swing getting smaller and smaller, this
> > > problem is getting worst. compound this with source sync
> > > buses where the strobes and data can behave differently
> > > (true differential vs. pseudo differential), i believe
> > > predicting the response of the receiver under different
> > > waveforms input will be as important as simulating
> > > the propagation of signal in the interconnect
> > > environment. this will be the final nail in the coffin for
> > > behavioral models like ibis which is totally incapable of
> > > handling such analysis. i have seen pitiful attempts to
> > > qualitatively describe it in ring back or edge rate
> > > extrapolation but without the ability to simulate the
> > > receiver behavior, those specs are just fancy words with
> > > no meaningful insight into the response of the true
> > > receiver.
> > > can i spell SPICE again.
> > > chris
> > >
> >
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