Abstract: A monolithic bulk acoustic wave (BAW) duplexer, and a method for fabricating same, the duplexer having a, transmitter section as a first component filter and a receiver section as a second component filter, both component filters fabricated on a single substrate and both including at least one shunt BAW resonator and one series BAW resonator, each BAW resonator including a resonator section atop an isolation structure provided so as to separate the resonator section from the substrate, including: a patterned bottom electrode material for use as the bottom electrode of each of the resonators of the duplexer; a patterned piezoelectric material for use as the piezolayer of each of the resonators of the duplexer; a patterned top electrode material for use as the top electrode of each of the resonators of the duplexer; a tuning layer for the shunt resonator of each of the two component duplexer filters; and a tuning layer for both the series and shunt resonators of one of the two component duplexer filters.