Is it possible to achieve phase consistency between two
ADF4159/ADF4169 PLLs ?
Two ADF4156 PLLs can be programmed to achieve phase consistency, in the datasheet this is explained in the PHASE RESYNC section. Unfortunately the ADF4156 does not have any modulation capability.
In the ADF4159/ADF4169 the phase word will only change the RF output phase relative to the current phase. It seems like phase consistency between two PLLs is not possible. But in the ADF4159 datasheet it also says that the sigma-delta modulator is reset on each write to R0 when the sigma-delta reset bit (bit 14, register R3) is 0.
If two ADF4159s are programmed simultaneously and have the LE input line in common (and naturally also a common reference frequency) it seems to me it should be possible to achieve phase consistency. After the write the two PLL counters should be in sync. It is of course required that there are no cycle slips in connection with the programming. To achieve this goal I was thinking on writing R0 with the same value that is already there.