An FBAR filter includes a wafer, a filter circuit unit and a balun circuit
unit. The filter circuit unit includes a plurality of FBAR resonators
formed on a predetermined region on a top of the wafer. The balun circuit
unit includes a plurality of metal layers electrically connected to each
other to implement a balun circuit and a plurality of dielectric layers
each placed between the plurality of metal layers. The balun circuit unit
is electrically connected to the filter circuit unit on a predetermined
region of the wafer.