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AD9364 Tx  In band  spurious 

Question asked by padma@1969 on Mar 9, 2017
Latest reply on Mar 26, 2017 by padma@1969

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.

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