The hittite IC company makes fixed dividers that operate at 10 GHz or so. I have not used them but have found that every product from them that I have used was better than the data sheet numbers. https://www.hittite.com/index.cfm?b..._div_det&catid=7&sort=function&source=leftnav is their selection chart. Note that they have dividers for prime numbers like 3 and 5 also as well as a 5 bit settable counter.