Hi Prasad,
Could you let me know how do you generate the LTE waveform? Did you generate this waveform from our HSDC PRO/TSW1400 LTE GUI? If so, the output waveform in .tsw format is encoded and may cause spectral issues.
I can generate a zero IF LTE for you if you would like. This may help us narrow down whether this is a waveform issue or DAC issue.
Could you also generate a two tone signal to test the IM performance just to check if you get the same spur performance? You may generate this on the HSDC PRO GUI, and then go to file > save as to save as a .csv file for you to import to your project. The single/multi-tone generator file is not encoded.
-Kang