I have two use cases I want to try. One where I'm using a 10MHz reference input, the other a 400MHz input. I can get it to work by Removing R12. But I just don't understand what the user guide is trying to tell me.
To use a single-ended REFINx, connect a low noise 122.88 MHz reference source to SMA REFINB, and connect a 50 Ω terminator to SMA REFINA. Remove Resistor R27 (100 Ω). To use a differential REFINx, connect the differential signal to SMA REFINA and SMA REFINB.
- Why would I have to connect a 122.88MHz reference to REFINB if I just want to use a single ended input on REFINA? Can't I just GND it or float it?
- I assume the 50 Ohm terminator on REFINA is to GND right?
- The datasheet for the ADF4355-2 says maximum single ended input frequency is 250MHz. It seems to run just fine when I put in a 400MHz single ended input on REFINA. What are the consequences of doing this?