i get this warning for every other port in the design. is it ok? or i need to do something?
Do you have an infinite bottom ground in your stackup that is used for all port ground references?
Can you show your substrate (stackup), and indicate where signal and ground layers are?
1) does this warning affects simulation accuracy ?
question: Do you have an infinite bottom ground in your stackup that is used for all port ground references?
answer: no, I don't.
For RF traces, I used CPWG lines. Due to this, the ground plane is on the same layer as RF which is layer L1. Layer L2 is most ground plane but with DC circuits routing in it.
2) I set cell/wavelength to 80 for above frequency range. is this good enough to provide accurate simulation results which corelates to measurement?
Dear Volker,
--- WARNING -------------------------------------------------------------------
The distance between the layout pins for port 2 is electrically large
above 5.02761 GHz, S-parameters may become unphysical.
-------------------------------------------------------------------------------
--- WARNING -------------------------------------------------------------------
The distance between the layout pins for port 9 is electrically large
above 5.20276 GHz, S-parameters may become unphysical.
-------------------------------------------------------------------------------
--- WARNING -------------------------------------------------------------------
The distance between the layout pins for port 10 is electrically large
above 5.20276 GHz, S-parameters may become unphysical.
my design has 55 ground pins and 127 signal pins. I didn't place the ground pins manually nearby to the signal ports. the ground pins are from the ground pads of the components. is it necessary to place ground pins nearby to each signal ports for reference? does it change the accuracy of the simulation?
I also manage to convert sheet metal into thick metal as you suggested. for two layer board, its only letting me to do it for bottom copper and not top copper.
--- WARNING -------------------------------------------------------------------
Layout is electrically large above 3.21 GHz (space wave radiation)
-------------------------------------------------------------------------------
--- WARNING -------------------------------------------------------------------
Substrate is electrically large above 34.5 GHz (surface wave radiation)
--- WARNING -------------------------------------------------------------------
The distance between the layout pins for port 2 is electrically large
above 5.02761 GHz, S-parameters may become unphysical.
-------------------------------------------------------------------------------
I manage to solve these problem by moving ground pins closer to the signal pins. now remaining warning is only as below;
yes you did explained in detail and this issue is solved. thank you.This is the issue that I described above: with finite ground, you need explicit ground pins.
Yes, ground path is equally important as signal path. Any extra length from ground pin in the physically wrong place means simulation error. How much error, that depends on the pin position error vs. wavelength.
Im designing PCB. I have intrude copper on layer L1 and expand copper at layer L2. I have attached the picture.I don't know what you did, but Momentum lets you define any layer as thick metal (intrude into dielectric above/below instead of thin sheet). I'm using that all the time in RFIC EM work. I recommend using thick metal model if your line/gap with is smaller than 5 * metal thickness, but that number is not a "hard" limit. It also depends on other settings like edge mesh.
View attachment 147507
Ok, I'm working through your post step by step. Please see comment above on this warning.
If you think more hands-on support would be useful for reliable results: My company also offers EM methodology consulting and EM training/coaching.
--- WARNING -------------------------------------------------------------------
Layout healing changed the layout. The actual
highest aggregate snap distance was 9.9694 mil.
Further details have been written to the DRC
report.
does it affects the accuracy? if yes, please let me know how to solve it?
Im designing PCB. I have intrude copper on layer L1 and expand copper at layer L2. I have attached the picture.
when I switch from momentum to microwave mode, all the warning above disappeared with only one more warning which is states as below;
I have another basic question. my simulation is EM cosimulation since im simulating the pcb layout and will do circuit simulation with components later. but when I select EM cosimulation, its not simulating. its only simulating in EM simulation/model. why is it so?
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