Re: [SI-LIST] : Routing Differential Pairs as 100 differentially Vs individually 50 ohm lines

About this list Date view Thread view Subject view Author view

From: Ritchey Lee ([email protected])
Date: Wed Nov 22 2000 - 09:38:00 PST

Those comments are from my class. That is exactly how differential
signals should be routed. Routing them close to each other produces
interaction that reduces the final amplitude. I route 2.5 GB
differential signals as two 50 ohm lines separated by at least 25 mils.


Gaboian, Jerry wrote:

> I am looking for some feedback on the topic routing LVDS differential
> pairs as 100 ohms
> with respect to each other Vs. 2 separate 50 ohm lines.
> At the PCB East conference several keynote speakers referenced the
> following comment:
> "No need to specify differential impedance between two lines. Routing
> traces side by side
> does not guarantee noise immunity from common mode noise. On the
> contrary, noise from an
> adjacent line will couple as a differential signal"
> The length of the pairs should be matched and kept close to a
> reference plane (about 5 mils)is the must important criteria.
> Comments, suggustions.......
> Thanks,
> Jerry Gaboian

**** To unsubscribe from si-list or si-list-digest: send e-mail to
[email protected] In the BODY of message put: UNSUBSCRIBE
si-list or UNSUBSCRIBE si-list-digest, for more help, put HELP.
si-list archives are accessible at

About this list Date view Thread view Subject view Author view

This archive was generated by hypermail 2b29 : Tue May 08 2001 - 14:30:13 PDT