In the KnowledgeBase, it was said:
"Momentum calculates Z0 when you are using Single Ports. But it's not calculated when using Internal Ports. Here is one example on how to find Zo by optimization."
Well, I generated a CPW layout from ADS's CPW. Then added P1 and P2 as single ports to the middle strip (P1 and P2: Single, 50+j0 Ohm, Reference=0).
Then I ran MoM-Simulation Adaptive mode. The .ds file is then displayed in data_display.
Where is Zo? I could not find the calculated Zo anywhere. (Performing an optim in schem. would be an alternatie).
I appreciate anyone's comments on this.
"Momentum calculates Z0 when you are using Single Ports. But it's not calculated when using Internal Ports. Here is one example on how to find Zo by optimization."
Well, I generated a CPW layout from ADS's CPW. Then added P1 and P2 as single ports to the middle strip (P1 and P2: Single, 50+j0 Ohm, Reference=0).
Then I ran MoM-Simulation Adaptive mode. The .ds file is then displayed in data_display.
Where is Zo? I could not find the calculated Zo anywhere. (Performing an optim in schem. would be an alternatie).
I appreciate anyone's comments on this.
Strip Model - For this, you need at least 3 strips to define the center conductor and the two outer ground strips. If you place a single port on the center strip and two Ground Reference ports on the outer strips, then Momentum will save the Z0 array for the CPW ports defined in the model.
Slot Model - For this, you define a Slot layer and draw two rectangles to define the slots of a CPW line instead of the strips. The slots are effectively cut out from an infinite metal plane. You then define CPW ports on the slots as defined in the manuals and Momentum will save Z0 in the dataset.
In either case, there are certain accuracy tradeoffs you may run into depending on the CPW dimensions, substrate properties, and conductivity of the metal. For example, if you have a slot model and a fairly lossy metalization, the Z0 values may not be accurate enough. Also if the metal is thick compared to the slot widths, you may not get a good enough Z0. In such cases, using a 3D strip model can be created, but it is too involved to explain in this forum. There is a Momentum Simulation Document that explains this in more detail:
http://edasupportweb.soco.agilent.com/cgi-bin/show.pl?id=141750
URL modified by support_admin @ Mar 3 2004