We us AD9789 as upconvertor and dac. We find that AD9789 RF outputs big noise at start up. The detail is:
After power up and reset, according to System start-up Sequence:
Enable the clock receiver and set the clock CML.
Enable duty cycle correction.
Then RF outputs big noise. From spectrum analyzer, DC to about 700 Mhz has high spectrum.
after finish step 4
Set up mu controller
RF spectrum is clear.
How to prevent RF start-up niose?