The standard mixer model in Spectrasys is giving erroneous results for IP3. The attached file has a mixer with specified IIP3 of 27 dbm. The simulation, both cascade / table and and manual calculation from the spectral output gives 29.4 dbm.
This is with version 2006.10.
I have attached the file.
[file]mixer ip3 error.wsx[/file]
This is with version 2006.10.
I have attached the file.
[file]mixer ip3 error.wsx[/file]
This issue has already been fixed internally and will ship in the next release. For those that can't wait for the next release please contact support.
The work around is to change the 3rd and 2nd order intercept points of the mixer. The 3rd order intercept point of the basic mixer (ONLY) can be lowered by 2.385 dB and the 2nd order intercept can be lowered by 3.01 dB. The intermod power levels on the graph and the OIP and IIP measurements will be correct. However, the SOIP and SIIP measurements (user entered values) will obviously not correspond to the calculated values.
The 'Double Balanced Mixer' and 'Intermod Table' mixers do not exhibit this problem.