Would you teach me the usage of Dither and Dither scale setting in the actual situation?
Can I use them to reduce the power of spurious ?
I am sorry to say, but the knowledge behind the dither settings of the AD9578 has been lost. Please use the explanations that are in the data sheet, page 39, tables 39 and 41.
Using the Quick startup setup file available on the AD9578 evaluation board website, I found the dither bits in registers 7 and 9 are not set. The frequency wizard does not set them, also. The data sheet does not explain how to use them. My conclusion is that they do not need to be used to achieve the performance indicated in the specifications tables.