ADF5356 Not Locking


I've made a board based on the recommended design but with a different ref clock and a single ended configuration. The loop filter remained as in the datasheet. Unfortunately, the MUXOUT pin never goes high (I've configured it for digital lock). Could someone throw some ideas out on what could be causing this? My suspicion is on either my reference in adaptation not being correct, or the loop filter is not working correctly. I've checked the signal at the DDS side of C1 and it looks to be biased around 2V with a swing of 1 volt, which should be ok. I do not know how to verify the loop filter is working as intended. The devices we use to program the 5356 works with the reference board that we have so the software side is correct (setting registers etc).

Also, what is the difference between analog and digital lock?


Attached is the schematic. Any help would be greatly appreciated!

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