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How can I do an EM Simulation of a circuit which includes microstrip and lumped elements?
Ahmet Mustafa Mungan
posted this on Feb 14 06:00
Hello,
I intend to design a tunable Combline filter with a varactor as a tuning element. I modeled the varactor with an inductance, a capacitance and a diode and I used that model as a subcircuit in the Combline filter topology. I achieved the simulations of the schematic succesfully. However, I don't know how can I do the EM simulations? Because I already know how to make EM simulations of circuits that includes only microstrip elements but I don't know how to do it with lumped elements like diode,capacitance and inductance?
Thanks,
Ahmet Mustafa Mungan
Istanbul Technical University
Electronics Engineering
Comments
In order to simulate this using the EM simulator you need to break the problem into 2 pieces. You can EM all of the distributed elements of the filter with ports placed at the locations where you want to attach lumped elements. Then in a schematic you can connect the EM structure to the lumped elements. Ideally you have better models for those components than ideal lumped ones (possibly s-parameters).
Well how can I connect the EM structure to the lumped elements to obtain the S parameters of whole system?
If you look at the example name RF_PCB_AMP1900.emp and look at the 4_RF_Layout_AMP1900 you can see how the lumped elements are integrated into the circuit using extraction. This can also be done by simply adding ports to the location where you want to connect the elements and then placing the EM structure as a subcircuit in the schematic along with the lumped elements. If you already have the filter in a layout then the extraction path is simpler.
Thank you so much Mr. Collins. Have a nice day.