[SI-LIST] Re: AW: Ground vias around signal via
- From: LI Yishan <Yishan.Li@xxxxxxxxxxxxxxxxxxxx>
- To: "Gert.Havermann@xxxxxxxxxxx" <Gert.Havermann@xxxxxxxxxxx>, "aaditya.kandibanda@xxxxxxxxx" <aaditya.kandibanda@xxxxxxxxx>, si-list <si-list@xxxxxxxxxxxxx>
- Date: Thu, 16 Oct 2014 07:39:50 +0000
Hi, Aaditya:
According to 3D simulation, ground vias around signal via deeply effect high
frequency impedance. If your signal is low speed signal, it seems the ground
vias are not necessary.
Best regards
Li Yishan
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Havermann, Gert
Sent: 2014年10月16日 14:59
To: aaditya.kandibanda@xxxxxxxxx; si-list
Subject: [SI-LIST] AW: Ground vias around signal via
Aaditya: My opinion is, if we have a proper return path, they are not
necessary.
-> As Wolfgang said, GND vias are needed for proper return path because without
any GND via there will be no proper return path. You don't have to put multiple
of those around the signal via. with proper placement one is enough even for
very high speeds.
Aaditya: Any situations they are useful other than shielding?
-> Placing many stitching vias doesn't necessarily provide any shielding.
That’s an old Myth. Take a look at waveguide filters. The placement of screws
into the dielectric (air) looks and functions very similar to a PCB where the
energy also travels in the dielectric. Stitching vias can act as a filter,
meaning that some frequencies are not shielded but guided to the outside.
Aaditya: How will they help? When do we need them?
-> As already said, use GND vias to provide a proper GND return. as a rule of
thumb there should be a return via within the range of 1/8 wavelength (Nyquist)
to the signal via.
BR
Gert
----------------------------------------
Absender ist HARTING Electronics GmbH, Marienwerderstraße 3, D-32339 Espelkamp;
Registergericht: Amtsgericht Bad Oeynhausen; Register-Nr.: HRB 8808;
Vertretungsberechtigte Geschäftsführer: Dipl.-Kfm. Edgar-Peter Düning,
Dipl.-Ing. Torsten Ratzmann, Dipl.-Wirtschaftsing. Ralf Martin Klein
-----Ursprüngliche Nachricht-----
Von: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] Im
Auftrag von Aaditya K
Gesendet: Mittwoch, 15. Oktober 2014 19:42
An: si-list
Betreff: [SI-LIST] Ground vias around signal via
Hello Experts,
I have a question on ground vias placement around signal via.
My opinion is, if we have a proper return path, they are not necessary. Am I
correct?
Any situations they are useful other than shielding?
How will they help? When do we need them?
Please help.
Thanks
Aaditya
------------------------------------------------------------------
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
------------------------------------------------------------------
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:
