Option 2 works for galvanicly isolated pairs like the antenna ribbon bill
mentioned. The only way this works is for the pair to be transformer
coupled. This is  more likely used in audio and RF but not typical high
speed digital.
On Sep 1, 2015 12:04 PM, <[log in to unmask]> wrote:

> Only in 2 instances:
> 1- If there is a "Broadside" GND trace directly under the pairs and on the
> same core.
> 2- If it's a single sided board.
>
> I don't think option 2 works very well.  Difficult to calculate.   There
> would need to be some other type of arrangement going on to fully support
> the
> integrity of the signals.
>
> IMHO,
> Cherie  Litson, IPC-CID+/CMIT
> Litson1 Consulting
> PCB Design Solutions &  Training
> 206-619-8844 [log in to unmask]
>
>
> In a message dated 9/1/2015 11:19:56 A.M. Pacific Daylight Time,
> [log in to unmask] writes:
>
> (not  painless planes..!)
>
> Has anyone ever heard of routing differential pairs  with no reference
> plane? (on  purpose?)
>
>
> ______________________________________________________________________
> This  email has been scanned by the Symantec Email Security.cloud service.
> For  more information please contact helpdesk at x2960 or [log in to unmask]
> ______________________________________________________________________
>
>
> ----------------------------------------------------------------------------
> -----
> DesignerCouncil  Mail List provided as a free service by IPC using LISTSERV
> 16.0.
> To  unsubscribe, send a message to [log in to unmask] with following text in
> the  BODY (NOT the subject field): SIGNOFF DesignerCouncil.
> To temporarily  stop/(restart) delivery of DesignerCouncil send: SET
> DesignerCouncil  NOMAIL/(MAIL)
> For additional information, or contact Keach Sasamori at  [log in to unmask]
> or
> 847-615-710_0  ext.2815
>
> ----------------------------------------------------------------------------
> -----
>
>
> _ (mailto:[log in to unmask])
>
> ______________________________________________________________________
> This email has been scanned by the Symantec Email Security.cloud service.
> For more information please contact helpdesk at x2960 or [log in to unmask]
> ______________________________________________________________________
>
>
> ---------------------------------------------------------------------------------
> DesignerCouncil Mail List provided as a free service by IPC using LISTSERV
> 16.0.
> To unsubscribe, send a message to [log in to unmask] with following text in
> the BODY (NOT the subject field): SIGNOFF DesignerCouncil.
> To temporarily stop/(restart) delivery of DesignerCouncil send: SET
> DesignerCouncil NOMAIL/(MAIL)
> For additional information, or contact Keach Sasamori at [log in to unmask]
> or 847-615-7100 ext.2815
>
> ---------------------------------------------------------------------------------
>


______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________

---------------------------------------------------------------------------------
DesignerCouncil Mail List provided as a free service by IPC using LISTSERV 16.0.
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF DesignerCouncil.
To temporarily stop/(restart) delivery of DesignerCouncil send: SET DesignerCouncil NOMAIL/(MAIL)
For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
---------------------------------------------------------------------------------