[SI-LIST] Re: Article discussion on bad packages

  • From: Chris Cheng <Chris.Cheng@xxxxxxxxxxxx>
  • To: "'si-list@xxxxxxxxxxxxx '" <si-list@xxxxxxxxxxxxx>
  • Date: Thu, 30 Dec 2004 12:05:46 -0800

Ray,
That's about what I remember how we did it before I left. And for package
resonance below 100MHz, the external PCB bypassing analysis can use the
simplified models. But the core FUB units and clock trunk needs the
transistor scale models to estimate the negative feedback on the current as
the supply collasp. That's another level of detail the board designer
doesn't need to know.


-----Original Message-----
From: Ray Anderson
To: si-list@xxxxxxxxxxxxx
Sent: 12/30/2004 10:43 AM
Subject: [SI-LIST] Re: Article discussion on bad packages

Chris Cheng wrote:

>Istvan,
>
>I would also like to ask the questions for one last time :
>a) Does SUN use IBIS or SPICE to analyze its critical IO or CPU core
power
>distribution ?
>b) Were you actually responsible to work on the CPU core power
distribution
>analysis for your company ? 
>I will be waiting till hell freezes over.
> 
>  
>
 One way I've done core PDN simulations on processors in the past was to

initially have the silicon design guys run  time domain transistor level

core simulations. These involved millions of transistor and took way too

long to run. From the time domain I vs T results of those simulations a 
behavioral model consisting of PWL current sources or PWL voltage 
controlled resistances was developed. We then utilized those behavioral 
models to characterize the time domain response of the core PDN's. It 
was always instructive to look at the p-p current excursions at the 
silicon, at various points in the package and finally at the PCB level 
to visualize the effects of the on chip, on package and PCB level 
decoupling networks. The behavioral models ran in seconds or minutes as 
compared to the transistor level models they were derived from which 
executed in terms of days or weeks.

-Ray Anderson
Senior Signal Integrity Staff Engineer
Xilinx Inc.
------------------------------------------------------------------
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:
//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:     
                //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: