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AD9361 - TX 3rd harmonic distortion (HD3) performance

Question asked by nsuzuki Employee on Sep 22, 2014
Latest reply on Oct 6, 2014 by tlili


I'm evaluating TX performance of AD9361.
Then, I found a problem when measuring TX 3rd harmonic distortion (HD3) via spectrum analyser.
AD9361 datasheet mentions that the TX 3rd order harmonic distortion (HD3) is over -35dBc@ATT=0dB and -50dBc@ATT=25dB.
However, actual measurement result cannot achieve these performance.
Here is the actual results.  TX frequency is 800MHz.
ATT= 0dB -> HD3=-11.86dBc
ATT=25dB -> HD3=-11.88dBc
ATT=50dB -> HD3=-11.89dBc

Does anyone advise me the reason of this behavior?