Hello. I'd like to ask about ADAS3022 AVDD powering.
I have +5v from DCDC on my board.
Do I need +5v from LDO for AVDD?
There is no requirement for using a Low Drop Out Regulator as long as you understand the potential sources of error that can be introduced through the supplies. Please note that the switching frequency for the regulator you are proposing falls within the 400-500 KHz range. In this range the ADAS3022 rejection is less than 50dB and thus you could see a significant portion of any switching energy in the output spectrum. Depending on the configuration and sampling rate you use for your configuration this energy could alias into a lower band and be difficult to filter out of your results during post processing. I would recommend measuring the output spectrum of the regulator under various load conditions to understand the spectral content on the output. You can do this with a spectrum analyzer or using your hardware with the ADAS3022 running at 1MSPS on a single channel to understand the coupling to the output. By running at full throughput you reduce the chance of aliasing during your measurement.
Hope that helps