Hi,

The question was more with regards to the higher order LO harmonic levels that are generated from the internal PLL synthesizer.

As per the data sheet the third order harmonic distortions are around @-30 dBc @1.4GHz and 2.4GHz @ 0 dB attenuation. But we observed third order harmonics in the final out put is around -14dBc @1.4GHz and -21 dBC @ 2.4GHz @ 0 dB attenuation in the evaluation board of AD9364. If This high harmonic levels of Tx / Rx LO is provided to an internal IQ Modulator/ Demodulator , then the performance of the IQ modulator and demodulator is degraded due to Phase imbalance and amplitude imbalance. why i am getting worst third order harmonics in my out put . please let me know to to improve odd order harmonics in the LO out put.

Thanks ,

lakshmi

I think you are referring from " TX Third-Order Harmonic Distortion (HD3) vs. Frequency" Figure 49 in UG-570.

If so this measurement result is for HD3 of DAC not the LO harmonics.

Internally LO is squared and you will see harmonics, you need to use filter to reject harmonics.