port calibration in EMX

Hi Anh,

EMX ports are not calibrated.  They will have end effects.  There is no de-embedding of ports.

With regards to edge ports vs internal ports, there is an Article on this on Cadence Online Support  Tips on Specifying Ports in EMX 

You may want to file a Case on Cadence Online Support if you have EMX questions.  The AE who picks up the Case will work with EMX R&D on your question.

best regards,

Tawna

Up to what frequency do you expect useful results with the uncalibrated ports of EMX?

That might be good to have access to AWR/Sonnet since the port group calibration is available with those tools. However, we don't have access so I'm also curious to know from Tawna.

Hi Frank,  this is a frequently asked question and R&D has asked me to write something up about this.   I perhaps should have only talked about the port article until I've written up the "calibration" article in full.  Stay tuned.

Hi Tawna, I'm looking forward to your article. Your colleague John Dunn from AWR has also written very good White Papers about grounding concepts (https://www.awr.com/resource-library/understanding-grounding-concepts-em-simulators) and port calibration (https://www.awr.com/resource-library/plethora-ports-making-sense-different-types-ports-em-planar-simulators).

Hi Frank,

EMX ports with local references are very similar to FEM gap ports.  The formulation is set up in a way that no physical structures need to be de-embedded.  EMX does not have a physical elements between the reference and the signal ports and may be different from other EM simulators in this respect and so port calibration may mean something else for different simulators. 

Hi Tawna,

Could you please clarify if EMX ports with local references are similar to the "internal ports" or to the "grouped ports" described in https://www.awr.com/resource-library/plethora-ports-making-sense-different-types-ports-em-planar-simulators ?

Hi Frank,

This is best discussed in a meeting so we can explain it carefully.  This is not a topic for the Community Forum.  We'll set up a meeting when you return from your holiday vacation.

Wishing you and your family Happy Holidays!

best regards,

Tawna

Hi Frank,

After re-reading my last comment, I realized I clarify what I said...).   To avoid any misunderstanding, we don't disclose Cadence proprietary information in the forum.  That is why I suggested a meeting instead of discussion here on the forum.

thanks!

Tawna

Hi Frank and Anh,

Here's a bit more information that I can share...

When using local references EMX ports most closely mimic “gap ports” used by finite element simulators.  The return current is forced through the reference port(s). EMX does not have an artificial feed structure that may introduce parasitics and hence there is no need for explicit calibration.  When EMX does not use a reference port then the assumption is that "gap" is from a node at infinity.  Again, there is no physical structure that connects the EMX port to the backside ground plane, and there is no calibration done. Unreferenced ports take charge from infinity and deposit it on the structure, and another port on the same conductor can take charge off the structure and deposit it back at infinity.  So the loop is being closed at infinity.

When using “radiation” or “full-wave” in EMX it is strongly recommended that local references be used.  In quasistatic mode or at low frequencies non-referenced ports usually provide a good answer. In the EMX formulation the line integral of the electric field along any path (including paths that pass through infinity) is equal to the sum of the source contributions along that path.

best regards,

Tawna