FEM Simulation of Thin Film Cap

Hi, I am trying to simulate a cap, one port and two ports simulation using FEM in ADS but I got a very different results. Please see the following figures for simulation 1 and and 2. I was wondering if you know which one is accurate and what I am doing wrong here.

Thanks and regards,

Mojtaba

附图/附件

Sub_2port.png

3D_2port.png

Sub_1port.png

3D_1port.png

It is difficult to see the port details in the first example.

Obviously, with your small device under test and the much larger ports, you need to be VERY careful with port de-embedding, and the path length for ground return current. So the second example looks bad to me, with return current having to flow all around the simulation box from port 1 to port 2. You would better place one lumped port between the two plates.

Thanks Volker,

I attached more zoomed version of first example. The second one results also does not seem correct but I need a two ports results for my cosim simulation. For port calibration I have used None.

Thanks and regards,

Mojtaba

附图/附件

3D_1port_fig3.png

> For port calibration I have used None.

This will give terrible results with FEM for your case. All the port length included as parasitics. Not useful here!

> The second one results also does not seem correct but I need a two ports results for my cosim simulation.

No, you can't create useful 2-port data unless you have a well defined (physical meaningful) ground in the model. What you are looking for is a model with pure series elements. That can be created with a 1-port simulation where you connect the (+) pin to one plate and the (-) pin to the other plate.
Group the two pins into one differential port in the port editor.


Then in the *symbol* you then need access to both (+) terminal and also the reference terminal. ADS allows you to create the reference pin in the symbol, and here you need that.

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