Re: Flight time measurements

Hi John,

  I see logic in your argument.
Did you actually write a bird last time?
To make IBIS work everyone must participate.
I hope you will consider submitting a BIRD
(buffer issue resolution document). This is basically
who,what,where,why, how with syntax. typically it would be
a one page document. The BIRD outline is at the IBIS site.
Actually if you submit the BIRD form it would start as an EGG
than grow into a BIRD if you get no major objections.

How about following the same syntax as the driver
dv/dt just to be consistent.

Best wishes
Kellee

At 09:26 AM 5/20/98 +0200, you wrote:
>Bonjour,
>
>Once upon a time, I proposed that IBIS 3.0 might allow
>input slewrates (V/ns or ns/V) be defined for a receiver:
> * SR1: "worst-case" slew-rate beyond which the receiver
> might oscillate
> * SR2: "best-case" slew-rate, the minimum for receiver
> timing to be valid.
>
>Having recently read the new GTL+ guidelines from Intel, available
>at http://developer.intel.com/design/Pentium/applnots/24373501.pdf,
>I think it's be worthwhile to fly this kite again...
>
>In paragraph 3.2 (pp 11-14) of the Intel document, the flight time
>calculation rules are:
>
> - if the input signal edge is faster than SR2 (0.3 V/ns),
> then flight-time is measured at Vref
> - if the input signal edge is slower than SR2,
> then flight time (for a rising edge) is obtained
> by extrapolating back to Vref, with a slope equal to SR2,
> from the crossing point with Vih.
> - if the signal is non-monotonic, then extrapolate back to Vref
> from the last Vih crossing point .... but with a different
> value of SR2 (0.8 V/ns).
>
>In my opinion, these are very sensible rules - even if I don't
>understand fully where 0.8 V/ns comes from.
>Unfortunately, IBIS does not allow SR2 to be specified.
>
>My questions:
>
> a) Do others on this list use these or similar rules?
> If so, what values do you use for SR2?
>
> b) Does the current generation of simulators allow for
> a SR2 parameter to be used in flight-time calculation?
>
> c) Would it be useful to add an entry under the [Model Spec]
> keyword to allow SR2 to be defined for a buffer?
>
>Regards,
>John
>
>--
>John Fitzpatrick <John.Fitzpatrick@ln.cit.alcatel.fr>
>Alcatel Telecom, 4 rue de Broglie, 22304 Lannion, France
>Tel: +33(0)2.96.04.79.33 Fax: +33(0)2.96.04.85.09
>
>
Received on Wed May 20 01:52:27 1998