[SI-LIST] Re: Ferrite Beads on Differential Signal Lines?
- From: Craig Francis <craigleefrancis@xxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Fri, 12 Sep 2014 14:11:37 -0700
SI-LIST,
Thanks for the insight.
My application is like Randy described: low data rates (think 1Mbps) driven
by microprocessors and cables between PCBs within a chassis.
Some people put ferrites on single-ended signals before the connector to
reduce the high frequency content of the signal and prevent unnecessary
high-frequency radiation.
Murata sells ferrite arrays for this purpose:
http://www.murata.com/en-us/products/emc/emifil/bl but I understand that
they are in the business of selling ferrite beads.
I was wondering why I never see the ferrites applied to differential pairs,
only common-mode chokes. But it sounds like there are better matched
filters for differential pairs to reduce common mode conversion.
However, there appears to be a large disagreement on using ferrites on
signal lines at all. Application notes and books offer contradictory
information and now I am more confused than I started.
Thanks,
Craig Francis
On Fri, Sep 12, 2014 at 2:04 PM, steve weir <weirsi@xxxxxxxxxx> wrote:
> Some generalizations are more general than others.
>
> Steve
> On 9/12/2014 8:47 AM, Orin Laney wrote:
> > All generalizations are false.
> >
> > -----Original Message-----
> > From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
> On
> > Behalf Of Lee
> > Sent: Friday, September 12, 2014 8:15 AM
> > To: clfranci@xxxxxxxxxxx; si-list@xxxxxxxxxxxxx
> > Subject: [SI-LIST] Re: Ferrite Beads on Differential Signal Lines?
> >
> > It makes no sense to put ferrite beads in any signal line. How did this
> get
> > started?
> >
> > -----Original Message-----
> > From: Craig Francis
> > Sent: Thursday, September 11, 2014 4:11 PM
> > To: si-list@xxxxxxxxxxxxx
> > Subject: [SI-LIST] Ferrite Beads on Differential Signal Lines?
> >
> > SI-List,
> > I haven't seen any literature concerning using ferrite beads on each
> signal
> > line of a differential pair.
> > Usually only a common-mode choke is used to reduce common-mode EMI.
> >
> > Can ferrite beads be used on a differential pair to increase the the rise
> > time of the signal and reduce unnecessary high-frequency content that may
> > radiate?
> >
> > The two ferrite beads would be sized to allow the bandwidth necessary for
> > the differential signal's highest data rate.
> >
> >
> > Thanks,
> > Craig Francis
> >
> >
> > ------------------------------------------------------------------
> > 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 forum is accessible at:
> > http://tech.groups.yahoo.com/group/si-list
> >
> > List archives are viewable at:
> > //www.freelists.org/archives/si-list
> >
> > Old (prior to June 6, 2001) list archives are viewable at:
> > http://www.qsl.net/wb6tpu
> >
> >
> >
> >
> > -----
> > No virus found in this message.
> > Checked by AVG - www.avg.com
> > Version: 2014.0.4765 / Virus Database: 4015/8184 - Release Date: 09/09/14
> >
> > ------------------------------------------------------------------
> > 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 forum is accessible at:
> > http://tech.groups.yahoo.com/group/si-list
> >
> > List archives are viewable at:
> > //www.freelists.org/archives/si-list
> >
> > 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 forum is accessible at:
> > http://tech.groups.yahoo.com/group/si-list
> >
> > List archives are viewable at:
> > //www.freelists.org/archives/si-list
> >
> > Old (prior to June 6, 2001) list archives are viewable at:
> > http://www.qsl.net/wb6tpu
> >
> >
> >
>
>
> --
> Steve Weir
> IPBLOX, LLC
> 1580 Grand Point Way
> MS 34689
> Reno, NV 89523-9998
> www.ipblox.com
>
> (775) 299-4236 Business
> (866) 675-4630 Toll-free
> (707) 780-1951 Fax
>
> All contents Copyright (c)2013 IPBLOX, LLC. All Rights Reserved.
> This e-mail may contain confidential material.
> If you are not the intended recipient, please destroy all records
> and notify the sender.
>
> ------------------------------------------------------------------
> 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 forum is accessible at:
> http://tech.groups.yahoo.com/group/si-list
>
> List archives are viewable at:
> //www.freelists.org/archives/si-list
>
> 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 forum is accessible at:
http://tech.groups.yahoo.com/group/si-list
List archives are viewable at:
//www.freelists.org/archives/si-list
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
