### Q

Please explain what harmonics ADF5355 has on output spectrum and if there isany sample screenshot of spectrum.

### A

ADF5355 data sheet rev. 0. Figure 17 show the harmonic content on RFOUTA+/-, soto read the data with 6GHz RFOUTA output you see the second harmonic at 12GHz

~-27dBc and the third harmonic at 18GHz at ~-28dBc.

Hence

(a) Figure 17 show the harmonic of the RFOUTA+/- signal, the x-axis is the

carrier frequency

(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

with 13.6GHz

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).