Dear all,
I'm testing LMX2571 evaluation board for synthesizing frequencies between 800MHz and 940MHz. On the RF output it is possible to detect a lot of spurs, depending on the set frequency. After making a lot of tests, it is evident that the spurs are generated at a frequency offset from the generated carrier, that is equal to the distance (in frequency) of the internal oscillator from the nearest n-th harmonic of the reference oscillator (osc in). This spur is directly coupled (by a kind of crosstalk) to the output RF line, without being affected by the loop filter.
These spurs are present at a significant level of -60/-70dBc up to about 10MHz of distance from the generated carrier and it is not possible to avoid this effect by loop filter, because the crosstalk is jumping it.
This is not affordable for a base station application. Please can someone help me in finding a possible solution to this problem?
Thank you,
best regards,
Mauro