I don't know in detail. Clearly the differential RX inputs must be able to pick up the signal from antenna coil. And the specified voltage range has to be kept. There might be additional Melexis application notes for PA connection in 15693 applications.
Referring to your previous question, the PA input must not necessarily be connected through a balun, it could also use a single ended TX output, I think. In this case, the load impedance should be not too low.