We are using FMCOMMS4 (Ref Freq 40MHz) with ZC706 EVB.

We are giving all 0's base band signal to AD9364. We are observing transmit spectrum in a spectrum analyzer.We are seeing spurious around 190KHz and its multiples away from the carrier.The spurious levels are as follows:

Tx RF PLL Freq. at 1.3GHz - 52dBc at 190KHz and lower levels than this at multiples of 190KHz.

Tx RF PLL Freq. at 1.5GHz - 52dBc at 190KHz and lower levels than this at multiples of 190KHz.

Tx RF PLL Freq. at 5.0GHz - 46dBc at 190KHz and lower levels than this at multiples of 190KHz.

We also notice that at certain Tx RF PLL frequencies (ex.: 4.5GHz, 4.7GHz,4.9GHz) the above spurious components are not observed. Incidentally these frequencies are not multiples of 40MHz Ref Freq. However this is not always the case (as indicated above spurious is observed at 1.3GHz and also at 1.5GHz. These two frequencies are not multiples of 40MHz Ref Freq.).

The above spurious levels appears to be causing errors in the Radio link. Please let us know the reason for this (Spur?) and suggest way to reduce the spurious.

There is a small correction to the above post in that the base band signal is all 1's, not all 0's.