Calculating Differential pair witout reference

[elec4fun]

Hello,

I'd like to know which model you are using for the calculation of diff pair when there is no reference signal. The chassis is connected to the connector shield pins.

For example :

- between an Ethernet transformer and its connector,
- if we had to connect directly two Ethernet connectors.

I know broad coupled model for strip line could apply here but it implies too much routing constraint.

Thanks in advance.
Franck.

 

[edaedaeda]

Crevars,
Here is an app note from polar in regards to edge coupling diff pair.

Characteristic impedance, copper thickness and edge coupled lines

Regards,
eda

 

[elec4fun]

Thanks for the link. That's exactly what I'm talking about.

However, that's not very clear In the evaluation of polar Si8000, I can't find the "Edge coupled differential pair without ground plane (Coplanar Strips)" they are using....

Franck.

---------- Post added at 21:52 ---------- Previous post was at 21:44 ----------

Okay, I found my answer here Characteristic impedance of coplanar strips (differential pair without ground)