QPlease explain what harmonics ADF5355 has on output spectrum and if there is
any sample screenshot of spectrum.
AADF5355 data sheet rev. 0. Figure 17 show the harmonic content on RFOUTA+/-, so
to read the data with 6GHz RFOUTA output you see the second harmonic at 12GHz
~-27dBc and the third harmonic at 18GHz at ~-28dBc.
(a) Figure 17 show the harmonic of the RFOUTA+/- signal, the x-axis is the
(i). The Second harmonic is the signal seen at 2x the carrier
frequency, so on the at x-axis at 1GHz carrier the second harmonic is at 2GHz,
and at 7GHz on x-axis you are looking at the harmonic at 14GHz
(ii) Third harmonic is the signal seen at 3x the carrier frequency, so
on the at x-axis at 1GHz carrier the third harmonic is at 3GHz, and at 7GHz on
x-axis you are looking at the harmonic at 21GHz
(b) Figure 20 show the VCO feed through on RFOUTB, so to read the data
on RFOUTB you see ~-4dBc signal at 6.8GHz
(c) RFOUTA+/- is only spec’ed to 6.8GHz, RFOUTB is spec’ed to 13.6GHz
Figure 21 show the same data on RFOUTB at 6.8GHz showing the wideband spectrum.
Figure 23 shows the PFD/reference spurs vs PFD frequency.
For optimum integer boundary spur performance, it is recommended to use the
single-ended setting for all references up to 250 MHz (even if using a
differential reference signal).