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Mixer Noise Figure Measurement with low IF frequencies

Question asked by mikejvir- on Apr 14, 2014
Latest reply on Apr 17, 2014 by tabbott
Hello All,

  I have a N8973 NFA and need to measure the noise figure on a mixer (downconverter).  The RF is 700 to 900 MHz.  The IF is 10 -100 MHz.  I need to measure both the upper and lower sideband.  I also need to do this over temperature. I will be using a ESG or MXG signal generator for the LO source.  I need the data to be presented as a function of IF frequencies (four curves,  RF = 700, 900 MHz,  LO swpet as both the upper and lower).

  Filtering is an absolute must due to the IF frequency.  I have the following ideas:

1)  Double Side band Measurement with a fixed LO.  No RF filter needed.  Use a band pass filter on the LO.   IF needed, break the IF band up so low pass filters  can be use to reject the LO signal.  Issue is I need data for only 700  and 900 MHz but with the IF stepped every 10 MHz (or 10 points).  Therefore I need 40 calibrations and measurements.

2)  Fixed RF.  I can set a bandpass filter on the RF (BW 5% or 35 to 45 MHz) so that a 4 MHz is flat and the signal is down 20 dB at 20 MHz offset (I realized I will not be able to measure 10 MHz).  I could use a low pass filter on the IF and under this condition I only need four calibrations and measurements.  The NFA only has a fixed LO/swept IF or swept LO/fixed IF mode.  Not sure how the NFA would be set up. (I do have a call into the Call Center but I figured I would ask here anyway).


Any comments (pro's, con's) or new ideas would be greatful.



Michael J. Virostko
Principal Product Application Engineer
Integrated Device Technology, Inc.
Westford, MA USA  

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