Hi,

I have question about new 1/f spec: I assume like the old PN_synth, PN_1/f is function of both F_comp and N, right?

in other word, to use this number to predict inband phase noise (< 20k), I have to use same Fcomp when this number taken by ADI, but I could not find it at DS.

Thanks

Jun

The old method of predicting in-band noise just used the FOM and FPFD and the N value. But the new method sums the noise from FOM (as before), and adds the 1/f noise contribution also.

The 1/f noise is different in that it does not depend on the N value, but rather depends on the PLL output frequency, and the offset at which the measurement is being taken.

Both these numbers (FOM and 1/f) should be calculated individually for the given PLL frequency, and then summed. But ADIsimPLL greatly simplifies this calculation and includes the contrubution of the reference, VCO and PLL loop filter. It's a free download www.analog.com/adisimpll.

Ian