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finite ground plane with global or differential ports

Question asked by jeff0283 on Sep 21, 2015
Hi, I am doing the em cosimulation of my board,which is the output matching of PA, and I want to see the difference between infinite ground plane and finite ground plane.

Here are my layout and substrate setup and schematic with finite ground plane.
(layout_finite.png),(substrate finite.png),(schematic_finite.png)
I set cond1(pink) as the top metal,and cond2(yellow) as the bottom metal. Because I use CPWG, the holes are placed to connect the cond1 with cond2.
Is it right for finite ground plane? 

For the port setup, I've tried two ways
1. I set all the pins as global ports:
2. I set (Pin1,10),(Pin2,11),(Pin3,13) as three differential ports,and other pins remain global ports.
But the results are different, I don't know why....
(result_finite.png)(red is for global ports and blue is for differential ports)
Could anyone give me some advice??


Edited by: jeff0283 on Sep 21, 2015 9:46 AM