I am evaluating the the IMD option 087 for PNA-X. I tried measuring the IM3 distortion of an amplifier. The frequency range of measurement is from 1G to 2GHz. I chose the Match Corrected Response Calibration and calibrate at the centre of two tone frequencies. I also enabled receiver leveling so that the actual incident power is accurate. During the measurement, I checked the input tone powers which are indeed leveled very well to within 0.02 dB ripples. But when I looked at the output tones, it was exhibiting greater ripples about (~ 0.12 dBpp ripples). My understanding is that the both input/output match of DUT and the receivers should have been corrected and we should see output ripples about the same as inputs. Am I missing something here ?
I noted that PORT2 light on the panel did not seem to flash, is it not doing reflection measurement and hence the output tone power is not corrected ?
For your info, I put 10 dB attenuator at the output of the DUT so as to protect the PNA-X in the above measurement. I tried removing that expecting greater o/p tone power ripple. But I am seeing about the same.
Appreciate any advice or input on this,