[SI-LIST] Re: Question about Simulation in Spectraquest
- From: Scott McMorrow <scott@xxxxxxxxxxxxxxxx>
- To: chris.cheng@xxxxxxxxxxxx
- Date: Thu, 09 Aug 2001 19:51:00 -0700
Chris,
I find myself agreeing with you more often than not.
I agree that it is time to rethink i/o timing methodology.
The days of specifying timing to the pins of devices
are over.
For high performance busses, we measure all timing
from die-to-die, from the input of the output buffer to
the output of the input buffer. This is the only way to
insure that all effects have been included and not
double counted.
best regards,
scott
--
Scott McMorrow
Principal Engineer
SiQual, Signal Quality Engineering
18735 SW Boones Ferry Road
Tualatin, OR 97062-3090
(503) 885-1231
http://www.siqual.com
Chris Cheng wrote:
> it seems like we are all victims of some poorly defined legacy
> i/o timing methodology that were used back in the days when
> dinosaurs rule the world. maybe its time to rethink the way
> we should define our i/o timing in the future.
>
> -----Original Message-----
> From: Venkataraman, Srinivas [mailto:srinivas.venkataraman@xxxxxxxxx]
> Sent: Tuesday, August 07, 2001 1:01 PM
> To: 'James Freeman'; Venkataraman, Srinivas; 'Todd Westerhoff'
> Cc: Coleman, Dave; 'we_r_frendz@xxxxxxxxx'; si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: Question about Simulation in Spectraquest
> Importance: High
>
> Sure. The adjusted interconnect delay method is a good way to do it if you
> do not have a good
> receiver model. For high performance buses with very fast edge rates and
> smaller cycle times (a few nS), the need to do the whole path will become
> inevitable.
>
> The input to the receiver is always important as that is the only way to
> understand what the tline and the discontinuties along the path are doing to
> the signal.
>
> -----Original Message-----
> From: James Freeman [mailto:freeman@xxxxxxxxxxx]
> Sent: Tuesday, August 07, 2001 12:09 PM
> To: srinivas.venkataraman@xxxxxxxxx
> Cc: Coleman, Dave; 'we_r_frendz@xxxxxxxxx'; si-list@xxxxxxxxxxxxx
> Subject: Re: [SI-LIST] Re: Question about Simulation in Spectraquest
>
> Hi Srinivas,
> The signal at the receiver is always of interest for signal quality
> purposes and in the case of poorly documented receivers, the only way to
> quantify the delay.
>
> Thanks
> Jim Freeman
>
> "Venkataraman, Srinivas" wrote:
>
> > The flight time will always remain the same and has nothing to do with a
> > well or poorly behaved
> > t-line. Whether the flight time is fast or slow depends
> > only on the dielectric constant of the substrate. This confusion is caused
> > because you are trying
> > to bucket the driver delay, receiver delay and the interconnect delay in
> > different bins. The best
> > way would be to model the whole path, driver input->interconnect->receiver
> > o/p and then quantify the
> > impact of fast and slow skew corners of the devices.
> >
> > Srinivas
> >
> > -----Original Message-----
> > From: Coleman, Dave [mailto:dave.coleman@xxxxxxxxx]
> > Sent: Tuesday, August 07, 2001 7:44 AM
> > To: 'we_r_frendz@xxxxxxxxx'; si-list@xxxxxxxxxxxxx
> > Subject: [SI-LIST] Re: Question about Simulation in Spectraquest
> >
> > Rahul,
> >
> > For a well-behaved transmission line circuit, you are correct - the fast
> > corner conditions will yield the min flight time. If you have a
> > not-so-well-behaved circuit (i.e., have signal ringback across threshold),
> > the fast corner conditions may cause the signal to settle later than for
> the
> > slow corner conditions, so you CAN get a larger flight time with the fast
> > corner conditions.
> >
> > Dave
> >
> > -----Original Message-----
> > From: whiz kid [mailto:we_r_frendz@xxxxxxxxx]
> > Sent: Monday, August 06, 2001 8:14 PM
> > To: si-list@xxxxxxxxxxxxx
> > Subject: [SI-LIST] Question about Simulation in Spectraquest
> >
> > Hi Gurus,
> > I have a question about the usability of the values
> > that spectraquest spits when doing a flight time
> > simulation. When I am doing a simulation with a fast
> > driver, fast transmission line, and fast reciever I am
> > more concerned with the Min switch time (Min flight
> > time). Is the settle time (max flight time) that SQ
> > displays a use ful parameter here??. Because to find
> > the max flight time u make use of the slow driver,
> > slow line, slow reciever. Am I missing some thing in
> > how to interpret the values.
> >
> > Regards,
> > Rahul.
> >
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