AnsweredAssumed Answered

Noise figure measurement question

Question asked by bruceb. on Jun 26, 2014
Latest reply on Jul 13, 2014 by Dr_joel
Good day,

I have N9875A with N4002A. I need to measure upconverter NF but the RF is at 30 - 31 GHz. IF is 1 - 2 GHz. (LO =29 GHz) Right now I am using 
a passive mixer to mix down to the IF, i.e. 1 - 2 GHz. So I have select "amplifier" measurement. For calibration, I have simply
measured the loss and added that into the output loss parameter - in the measurement setup. No filters or anything on the output. Noise source is connected directly to the DUTs input. 

More specifics: Gain of UUT is about 34 dB. Loss of mixer is about 10 dB. Cable loss is about 1 dB. Power out of UUT is ~ 0dBm. 

I am getting higher than expected values - should be ~10-11 dB, I am getting ~13 - 15 dB. Is there something I am overlooking here?  Should I be calibrating out the mixer (and cables, etc.) directly somehow? Do I need a filter on the output of the mixer? The only filter I have  that will pass the full 1 - 2 GHz band is low pass.

I would appreciate any assistance on this.