we are trying to tune Antenna use DTM over UART from examples.
It is works fine for AAAA IC but doesnot for AABB IC.
Why, what's possible problem?
so this is a non-question. You have actually provided no details. You haven't said how you're trying to tune the antenna, you haven't said what 'works' means nor what 'doesn't work' means. You've posted no code you've actually given no details beyond "i'm trying to do something and it doesn't work".
Please go back to the drawing board and post a proper question which has enough detail .. some detail at all, which might allow someone to even start guessing where you've gone wrong.
I suspect this has nothing at all to do with antenna tuning but is all about running code on different variations of the chip and not linking it to correctly find the RAM but your question is so vague and lazy it's not even worth pointing you to the 500 times that's been discussed on the forums.
Also note that there are changes in HW design for nRF52840_AABB so your HW might be simply bad.