[SI-LIST] Re: PCI Express AC Coupling
- From: steve weir <weirsi@xxxxxxxxxx>
- To: "Bowden, Ivor" <ibowden@xxxxxxxxxxxxxxxxx>
- Date: Thu, 11 Mar 2010 14:39:09 -0800
All capacitors have some leakage. If you have a really clean PCB and
the static builds up faster than the leakage can drain it off you might
have an issue. Although I have never heard of a failure actually traced
to this mechanism, a 10K - 1M drain or shunt resistor should take care
of any such concerns. The biggest impact of such a solution is the
additional parasitics. In that respect, I think the drain resistor is
easier to implement transparently than the shunt is.
Steve.
Bowden, Ivor wrote:
> I wonder about having 2 series capacitors in a signal line. Could the
> floating node be subject to a static voltage buildup due to no DC path to
> ground? Enough to damage the capacitor (ESD event for example)?
>
> -Ivor
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
> Behalf Of Michael Rose
> Sent: Wednesday, March 10, 2010 2:47 PM
> To: Chris Johnson; si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: PCI Express AC Coupling
>
> Chris, I thought PCIe required AC coupling on both ends(?). Generally, I like
> to place the coupling caps on the RX end since the channel attenuates the
> slew rate making the impedance discontinuity a bit less severe. In some
> cases, AC coupling on both ends has the advantage of tolerating a short
> circuit through the interconnect without damaging the driver.
>
> Mike
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
> On Behalf Of Chris Johnson
> Sent: Wednesday, March 10, 2010 4:37 PM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] PCI Express AC Coupling
>
> Could someone tell me if any of the TX (from motherboard to card), RX (from
> card to motherboard), and REFCLK (from motherboard to card) PCI Express
> differential pairs are guaranteed to be AC coupled on the motherboard?
>
> Also, is there significant signal integrity downside to AC coupling on the
> plug in card, when the signals are already AC coupled on the motherboard,
> assuming that the AC coupling is right at the I/Os to the chip on the plug in
> card?
>
> Thanks,
>
> Chris
>
> ------------------------------------------------------------------
> 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.net
>
> 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 technical documents are available at:
> http://www.si-list.net
>
> 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
>
>
>
> _______________________________________________________________________
> This e-mail and any files transmitted with it are proprietary and intended
> solely for the use of the individual or entity to whom they are addressed. If
> you have reason to believe that you have received this e-mail in error,
> please notify the sender and destroy this email and any attached files.
> Please note that any views or opinions presented in this e-mail are solely
> those of the author and do not necessarily represent those of the
> Curtiss-Wright Corporation or any of its subsidiaries. Documents attached
> hereto may contain technology subject to government export regulations.
> Recipient is solely responsible for ensuring that any re-export, transfer or
> disclosure of this information is in accordance with applicable government
> export regulations. The recipient should check this e-mail and any
> attachments for the presence of viruses. Curtiss-Wright Corporation and its
> subsidiaries accept no liability for any damage caused by any virus
> transmitted by this e-mail.
> ------------------------------------------------------------------
> 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.net
>
> 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
150 N. Center St. #211
Reno, NV 89501
www.ipblox.com
(775) 299-4236 Business
(866) 675-4630 Toll-free
(707) 780-1951 Fax
------------------------------------------------------------------
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.net
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:
