RFC: DDS-board draft 2020-06-02

I would welcome comments and suggestions from experienced designers that have worked with laying out 4-layer boards for e.g. AD9912 and ADF4351 (or similar RF ICs) used in the microstepper DDS-board:

I will send out a PCB-order for the first prototypes in a few weeks. Schematic/PCB can be found from the PDFs above or kicad sources from the repository: https://ohwr.org/project/microstepper/tree/master/ddsboard

This board is part of the microstepper, block-diagram and function explained in the wiki: https://ohwr.org/project/microstepper/wikis/Block-diagram