[SOLVED] ADS Layout Simulation Warning

[aini_]

Hi!

What should I do to remove the following WARNING which shows like this:

WARNING: Accuracy can be lost due to matrix compression, you can rerun the simulation
with reduced compression level or with the direct dense solver to verify the results.

WARNING: S-parameter data show unphysical behavior for certain frequencies.

CAUSE:
1. electrically large port size
2. electrically large via using lumped model
3. mesh density is too coarse
4. matrix solver compression is too high
5. inaccurate (high frequency) calibration

Thank you.

 

[BigBoss]

Are there very wide planar patterns that are tied to ports ??

 

[arman12369874]

Are there very wide planar patterns that are tied to ports ??

Yes. I have the same problem with a structure as you mentioned. it is wide planar structure with a lot of ports.
And the response each time change by increasing the mesh.
I aslo change the cpression level from Normal to reduced but it doesn't help.

 

[BigBoss]

Yes. I have the same problem with a structure as you mentioned. it is wide planar structure with a lot of ports.
And the response each time change by increasing the mesh.
I aslo change the cpression level from Normal to reduced but it doesn't help.

The ports which are tied to large planar structures are generally calibration error sources. Therefore they should be converted into "Edge" type ports. Double clic on a port and change its type then assign a reasonable length in second field.

 

[volker@muehlhaus]

Double clic on a port and change its type then assign a reasonable length in second field.

Exactly, if you place a "normal" port on wide ground planes that port will extend over the complete edge length -> wide port -> no longer small compared to the wavelength -> port result not valid (and not the expected location of current flow).

The solution is what Bigboss showed: place a small, controlled port width instead, at the location that makes physical sense. For coplanar port grounds, I usually place the ground pins with a similar width as the center (signal) pin, close to the gap. That is where CPW ground current physically flows.