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