Hi,
Yes;
the Single ended Trace can be used in the Uncoupled routing length to reduce
impedance discontinuities and to match length.
The trace need to transition from its Differential (100/85 ohms) Trace spec
to its equivalent Single ended (50/42.5 ohms) trace spec (changing from
tight coupling to Loose coupling);
- so that the intra pair length matching can be achieved with any
required serpentines/zig-zag patterns in single ended routing.
Also, this need to be implemented wherever unavoidable discontinuity occurs
(uncoupling of diff pair due to AC-caps, Vias, etc) along with minimized
length matching localized to each discontinuity.
Regards,
Nathan J
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Amit Kumar
Sent: Tuesday, May 12, 2015 8:10 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Skew vs length matching
Hello guys,
I am making a board using a FPGA whose serdes runs on 12.5 Gbps.
Owing to the FPGA ball map, the diff pair routing on the PCB has about 1mm
of intra pair skew.
1 mm of skew translates to about 7-8 ps of electrical skew which I suppose
can't be ignored.
Now if I do length matching, we will have uncoupled zigzag routing(of ~1mm)
on one of the signal. Question is : Is it ok to do length matching in such
cases?
Regards
Amit
------------------------------------------------------------------
To unsubscribe from si-list:
<mailto:si-list-request@xxxxxxxxxxxxx> 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>
//www.freelists.org/webpage/si-list
For help:
<mailto:si-list-request@xxxxxxxxxxxxx> si-list-request@xxxxxxxxxxxxx with
'help' in the Subject field
List forum is accessible at:
<http://tech.groups.yahoo.com/group/si-list>
http://tech.groups.yahoo.com/group/si-list
List archives are viewable at:
<//www.freelists.org/archives/si-list>
//www.freelists.org/archives/si-list
Old (prior to June 6, 2001) list archives are viewable at:
<http://www.qsl.net/wb6tpu>
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
