PCB differential vias

How to use openEMS. Discussion on examples, tutorials etc

Moderator: thorsten

Post Reply
daver
Posts: 3
Joined: Tue 12 Mar 2013, 03:49

PCB differential vias

Post by daver » Tue 12 Mar 2013, 03:52

Has anyone attempted modeling differential vias on a PCB to obtain 4 port S-parameters?

thorsten
Posts: 1438
Joined: Mon 27 Jun 2011, 12:26

Re: PCB differential vias

Post by thorsten » Tue 12 Mar 2013, 11:53

Can you be a bit more specific? 4 port S-Parameter are no problem, but what do you mean by
differential vias on a PCB
?

regards
Thorsten

daver
Posts: 3
Joined: Tue 12 Mar 2013, 03:49

Re: PCB differential vias

Post by daver » Tue 12 Mar 2013, 16:31

Thanks for the reply,

Differential vias are a pair of vias on a printed circuit board that share a common anti-pad. They are used to transition a differential pair between layers.

http://www.ee.washington.edu/research/l ... 091707.pdf

Actually, If there is an example of a single PCB via that is available that would be very helpful too.

Thanks

thorsten
Posts: 1438
Joined: Mon 27 Jun 2011, 12:26

Re: PCB differential vias

Post by thorsten » Tue 12 Mar 2013, 16:41

Hi,

doesn't look to complicated to do?

The vias would just be cylinders and the antipad (it means missing metal right?) could be modeled using a polygon (of air with a higher priority than the metal) ...

What does this have to do with 4-port S-Paramters?

regards
Thorsten

daver
Posts: 3
Joined: Tue 12 Mar 2013, 03:49

Re: PCB differential vias

Post by daver » Tue 12 Mar 2013, 22:15

4 port s-parameters is the conventional way this structure is conveyed to signal integrity simulators. Same way that a single via would be a 2-port s-parameter (one port at each end of via, each ground referenced).

Normally HFSS and ADS are used for this (neither of which I have). I was just wondering if anyone has gotten satisfactory results modeling this with openEMS.

Thanks

sebastian
Posts: 114
Joined: Mon 27 Jun 2011, 12:36
Contact:

Re: PCB differential vias

Post by sebastian » Tue 12 Mar 2013, 23:28

Instead of ADS, use qucs to do circuit level simulations.
OpenEMS can be used to extract the via behaviour: use AddMSLPort to create the needed number of ports and process them with calc_ypar. This gives you the Y matrix, which can be transformed into S parameters. To get accurate results, the mesh needs to be fine.

A 2.5 D solver is more suited for this kind problem, check Sonnet.

Sebastian

Post Reply