[SI-LIST] Re: Power Supply Distribution/Filtering/Decoupling Guide
- From: steve weir <weirsp@xxxxxxxxxx>
- To: hassan@xxxxxxxx
- Date: Mon, 12 Jan 2004 23:11:42 -0800
Hassan, with all due respect, I believe you are taking Chris' comments out
of context. If you follow his earlier comments, I think you will find that
he is very clear on the need to design the entire power system. Chris
emphasizes that a lot of people are focused on trying to fix at the PWB
level problems that are either in the Si/package, or not really there at all.
Scott and Martin both point out the dearth of adequate information on the
Si/package combination leaves us guessing as to what is needed at the board
level to care for and feed a given device. It is very suboptimal to have
to guess at, or create characterization fixtures for IC's that the mfgs.
darn well better have designed and validated properly. Yet that data is
not getting to the integrators who the mfg's want to sell their IC's to.
As a tool vendor, this situation is probably an opportunity for you to sell
tools to the chip mfg's that will allow them to readily and cost
effectively provide the data that we as integrators sorely need.
Steve.
At 01:32 AM 1/13/2004 -0500, Hassan O. Ali wrote:
>I'm afraid this discussion is getting into over-generalization and
>over-simplification of the problem in question.
>
> Chris Cheng says:
>
> > if you have
> > poorly design chip and package, you need a hell of a lot of decoupling and
> > BC planes to fix it at the system level
>
>That is one example of generalization. Not every device-level power
>distribution flaw can be solved at the board level. As a matter of fact,
>many papers/documents I've read so far on this subject do clearly
>indicate the limitations of the PDS at the board level. The board-level
>PDS design only focuses on providing the power quality at the device's
>power pins/balls.
>
>Contrary to what Chris Cheng wants us to believe, you cannot
>realistically meet all power distribution requirements by focusing only
>on the device level. For one thing, the power comes from outside the
>device, right? How can you then ignore the path through which the power
>goes through before entering the device! Will the power delivered
>through two backplane connectors and a 60-in backplane trace be of the
>same quality as that delivered through an inch of fat PCB trace?
>Certainly not.
>
>Hassan.
>
>
>
>Scott McMorrow wrote:
>
> >Chris is correct.
> >
> >This was exactly my point previously. Without knowledge of the silicon
> >and package power distribution it is impossible to perform an analysis
> >of the entire power distribution system. But a well designed piece of
> >silicon and package will require very little support from the PCB.
> >
> >scott
> >
> >
> >Chris Cheng wrote:
> >
> >
> >
> >>I disagree. No one should be surprised. I have said many times, there is
> >>never a need for fancy decoupling scheme on PCB for properly design
> >>processor and package. Nothing should be need for >100MHz core noise and
> >>signal return is a case of reference plane management (does that sound like
> >>a broken record yet ?)
> >>
> >>
> >>
>
>
>------------------------------------------------------------------
>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 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
>
------------------------------------------------------------------
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 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:
