ADRV9008BBCZ-2 Transmits lots of spurious/harmonic signals.

Hello Zone,

We hope you are all well. 

We have a trouble with ADRV9008BBCZ-2. We use ADRV9008-2 in our board but there are too many harmonic and spurious signals occur at the output of the chip. A few posts on this subject were also shared in the ADI Zone but the answers were not clear to us. We were able to do some cleaning by using external bandpass and low-pass filters on the analog side for these harmonic and spurious signals, but especially the 4th and 8th harmonics disturb our chain. Our fundamental modulated waveform frequency is in L-Band frequency and is 1700MHz.  

For this chip, we use a schematic similar to ADRV9008-2 Eval Board. 

In general, our questions are as follows:

1- Is this harmonics and spurious behavior natural for the ADRV9008-2 ? Then our solution will be just using external filters on the board ? There is a post which someone faces a similar problem on this link:  

https://ez.analog.com/wide-band-rf-transceivers/design-support-adrv9008-1-adrv9008-2-adrv9009/f/q-a/543873/adrv9009---lo-harmonic-in-vhf-band

2- If it is not an inherent problem, then what are the solutions or guides that you can suggest to us ? Our clock frequency is 122.88MHz.

These harmonics and spurs begin to appear right after converting the chip's differential output to a single-ended line. When we measure just the output of the chip on channel power mode with the analyzer, we pay attention to the output without saturating the chip.

Attached are our measurement results. We would be very grateful if you could guide us on this matter.

ADRV9008-2 Single-Ended Output:

Filter 1:

Filter 2:

Filter 3:

Filter 4:

Thanks for your help.

THANKS.