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PNAX Enhanced Response ECAL Problem with Reverse Sweep

Question asked by andyTPE on Sep 21, 2012
Latest reply on Oct 8, 2012 by Spacecase69

I am being challenged by a PNA-X calibration issue.  I have several channels setup on my PNA-X for production test of an amplifier in which the hardware configuration of the channels is the same (avoid attenuator switching and mechanical switching of IMD paths).  On relevant channels I am using Enhanced Response calibration to avoid the reverse sweep.  

On one channel I am performing a power sweep to obtain amplifier compression data.  I perform a Enhanced Response calibration on this channel with src/rx power calibration - it simplifies automation of the calibration setup and I hope I am getting a little mismatch correction thrown in for free.  I have some source attenuation on the Port 2 source attenuator (for other channel considerations), but would think that this should not matter for this channel.  However, when I initiate the cal, I get a Unleveled source 1, out 2 error.  This occurs because my Pstop in the power sweep cannot be achieved with my P2 source attenuation value.  However, given that this is a Enhanced Response calibration, I would have thought that the mismatch error terms are all obtained by driving Port 1 (3 P1 reflection terms, load match and transmission tracking).  Thus I do not know why Port 2 gets driven (and hence causes my unleveled error message) - the little blue light tells me that Port 2 gets driven :(

Does the src/rx cal part of the cal cause P2 to be driven?  Is there a way I can workaround this unleveled issue?