The phase changes every time we configure the NCO of AD9177

Hi NgocHuong 

Thanks for using AD9177.  Please allow the product owner (landsman, kberry) to review your queries and provide update.

Thanks and kind regards,

Alex

To change FTWs with phase continuity you will need to use FFH with the DDSM_HOPF_CTRL0[7:6] set to 00 (default value). Please reference the section "Transmit Main Path FFH NCO Mode" in UG-1578. Updating the main FTW (just overwriting the FTW to the main NCO and strobing to take effect) will reset the accumulator phase when the new FTW is latched. Updating via the FFH process (hopping to pre-programmed FTWs in the FFH registers) will operating using the given hop continuity setting in DDSM_HOPF_CTRL0[7:6] (phase continuous, phase coherent, or phase discontinuous). You can update these pre-programmed FFH FTW registers at any time before hopping to them as desired.

After using FFH, the phase no longer changes. But frequency accuracy of the 32-bit NCO is insufficient for our application. I wonder is this possiable to use 48-bit FTW0 to solve this phase issue?