We are evaluating chip for using it in 4 to 5GHz band using z706 and FMCOMMS4 boards. what we have noticed is
IF LO frequency is at multiples of reference oscillator say 40MHz in our case . we are getting inband spurious as below
@188k level is -46dbc (RF Tx LO=4.4GHz, ref oscillator freq=40mhz ,and 110 harmonic of ref oscillator is 4.4GHz)
@376k level is -60dbc(RF Tx LO=4.4GHz, ref oscillator freq=40mhz ,and 110 harmonic of ref oscillator is 4.4GHz)
If difference between RF Tx LO and RF Rx LO frequency is 1MHZ .then harmonics of 1MHz are observed irrespective of reference frequency harmonics.
If RF Tx LO is at 4.5GHz which is not multiple of 40MHz and RF RxLO is 4.401GHz,then also we have noticed ,
How to resolve the issue with AD9361. what extra tuning or hardware i need .Please give advice to proceed further.