[SI-LIST] Re: Spread Spectrum Clock Synthesizers

Some processors will not tolerate a SS modulated clock.  Ask your vendor to
be sure.


Tom Dagostino
Teraspeed Consulting Group LLC
Device Modeling Division
13610 SW Harness Lane
Beaverton, OR 97008
503-430-1065
tom@xxxxxxxxxxxxx <mailto:tom@xxxxxxxxxxxxx>


Teraspeed Consulting Group LLC
2926 SE Yamhill St.
Portland, OR 97214
http://www.teraspeed.com <http://www.teraspeed.com>

Teraspeed (SM) is the service mark of Teraspeed Consulting Group LLC


-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of steve weir
Sent: Friday, April 30, 2004 6:04 PM
To: Shiraz.Bashir@xxxxxxxxxx; 'si-list@xxxxxxxxxxxxx'
Subject: [SI-LIST] Re: Spread Spectrum Clock Synthesizers


Shiraz, what happens is that phase errors result from the transfer function
of the slave devices.  How much phase error depends on the sweep rate of
the SS modulator, and both the bandwidth and damping of the PLL that is
attempting to track the SS modulated clock.

SS modulators don't reduce EMI, they reduce the the peak amplitude seen by
a narrow band filter as is used in the EMI tests.  The energy is all there,
it just isn't as coherent.  It is a legitimate way to buy regulatory margin.

As to your question about what specifications to look for, you have to
start out with your timing budget and work backwards from there.

Steve.

At 05:39 PM 4/30/2004 -0500, Bashir, Shiraz (MED) wrote:
>HI,
>
>Does any body has experience in using Spread Spectrum Clock Synthesizers/
>Driver (similar to CY2287).
>http://eent3.sbu.ac.uk/units/ade/warpdocs/CDrom/CDROM/DOCS/PRODUCT/CLOCK/CY
2
>287.PDF
>
>My question is what happens when a PLL (CY2287) output is fed into another
>PLL (inside Motorola MPC8270ZU microprocessor) ?
>
>Spread Spectrum Clock Synthesizers manufacturer claim that they reduce EMI
>as compared to non-modulated parts.
>
>Also what specifications should I look at while selecting a Spread Spectrum
>Clock Synthesizer to meet my system requirement (i.e., MPC8270ZU).
>
>Thanks,
>shiraz
>
>
>-----Original Message-----
>From: si-list-bounce@xxxxxxxxxxxxx
>[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of mahamud khandokar
>Sent: Friday, April 30, 2004 3:42 PM
>To: si-list@xxxxxxxxxxxxx
>Subject: [SI-LIST] Ansoft Nexxim? versus Hspice
>
>
>Dear All,
>
>
>
>can anyone tell me which one is the best for simulation:
>
>
>
>Ansoft Nexxim(tm)  or  Hspice
>
>
>
>please tell me something positive/negetive ,if anyone used this new
software
>before.
>
>
>
>I need to buy one of them for my company. we are PCB design based company.
>
>
>
>Thanks.
>
>
>
>Misty
>
>
>
>
>
>---------------------------------
>Do you Yahoo!?
>Win a $20,000 Career Makeover at Yahoo! HotJobs
>
>------------------------------------------------------------------
>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:
>http://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:
>                 http://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:
>http://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:
>                 http://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:
http://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:
                http://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:
http://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:     
                http://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: