PXIe-5668 Have High Spurs In Low Frequency Bands

Updated Oct 23, 2023

Reported In

Hardware

  • PXIe-5668

Issue Details

When you used PXIe-5668 to measure one CW signal at frequency lower than 3.6GHz , you will see some spurs in the low frequency bands , like below picture :

spur showing in 5668.jpg

When you measured the CW signal at high frequency bands ( higher than 3.6GHz) , you will not see the spurs;
Check the spec of PXIe-5668 , you will see below data :


MicrosoftTeams-image (56).png

So what you see is an expected result ,  why is there a big difference between lower frequency bands and higher frequency bands ?
 

Solution

Check the hardware diagram of PXIe-5668 , you will see below picture :

MicrosoftTeams-image (57).png


You will see there are two hardware paths for different frequency signal ; There is one YTF filter for the high frequency( over 3.6GHz)  , but there is no YTF filter for the signal which frequency lower than 3.6GHz ;  So you will see different result about spurs for different frequency signal;
 

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