does two identical AD DDS had a correlative phase noise upon synchronization mechanism apply ?
phase noise after mixing two identical and synchronized DDS are the same as if I mix a splitted single DDS ?
May I know the specific product that you are referring with like is it AD9910, AD9914, etc. On the meantime, please give me a moment to think more about your inquiry. Thanks.
I work with AD 9915.
i afraid that there is amount of noise that is differ between two identical chips so work with two DDS will degrade the phase noise cancellation
In your inquiry, you mentioned that you'll be mixing two identical DDS. The 2 signals coming from the splitted single DDS are closely correlated and this would yield a slightly better P/N performance than independent synchronized DDS.
Independent synchronized DDS will have independent phase noise contributions. The individual phase noise would be contributed from both supply noise and system clock source noise. The effect coming from these clock source noise would become significant especially if these have passed through a PLL for frequency multiplication.
let me verify my understanding - you wrote about internal DDS mechanism ?
the assumption is that there is common supply source and common clock tree.