FEM vs. Momentum simulation in ADS 2009U1

[raed_microwave]

Hi

I'm designing LNA in x-band and I simulate the layout in Momentum and FEM simulation and I found a big different between the simulated results and I think the problem that there is shifting the operating frequency to the lower frequencies. Please help me... in which simulation results I can believe??? below you can see the attached simulated results of LNA

 

[amitsinghjiit]

Hi

I'm designing LNA in x-band and I simulate the layout in Momentum and FEM simulation and I found a big different between the simulated results and I think the problem that there is shifting the operating frequency to the lower frequencies. Please help me... in which simulation results I can believe??? below you can see the attached simulated results of LNA View attachment 78621

Simulation results accuracy depends a lot upon the simulation settings, For Momentum, you need to set high Mesh cells/wavelength, edge Mesh as auto determine and Thin layer overlap to aggressive.
For FEM, check the delta error, make it 0.005, and consecutive passes to delta error required to 2 and Maximum number of adaptive passes to 50.

This is tough setting for accuracy, so you will have to trade off the performance of the simulator. Both the simulators are equally good, the only thing you need is the correct settings for your Simulators and they should end up fairly close to each other.

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Amit
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[johnjoe]

Also be careful with internal ports in FEM, they have an additional inductance. It really depends how you simulate your structure. Which technology is the LNA?

Greetings

 

[amitsinghjiit]

you can join ADS group to get your ADS related issue solved in no time

 

[raed_microwave]

I'm using s-parameters of NE3511S02 transistors....I'm designing LNA on substrate Rogers 4003C with h=0.51mm

 

[rodgerwxh]

I would suggest do a convergence study, first make sure that you configuration on FEM and Mom are exactly the same. Then start from coarse, refine your mesh little by little and MoM and FEM solution should converge to the same place. Otherwise, something else is going on.