Hi,
It's just a question of topology election(I assume you are talking of MB-UWB with channels of 528MHz): if you made a broadband LNA that covers all the bandwidth you don't need to do band selection in the LNA, if you prefer to use a "narrowband"(not so narrow after all) you will need to made typically input and output tunable inductors(like for example stacking inductors, but stacking could change the properties of the inductors).
Hope it helps,