One embodiment of the film acoustically-coupled transformer (FACT) includes a decoupled stacked bulk acoustic resonator (DSBAR) having a lower film bulk acoustic resonator (FBAR) an upper FBAR stacked on the lower FBAR, and, between the FBARs, an acoustic decoupler comprising a layer of acoustic decoupling material. Each FBAR has opposed planar electrodes with a piezoelectric element between them. The FACT additionally has first terminals electrically connected to the electrodes of one FBAR and second terminals electrically connected to the electrodes of the other FBAR. Another embodiment has decoupled stacked bulk acoustic resonators (DSBARs), each as described above, a first electrical circuit interconnecting the lower FBARs, and a second electrical circuit interconnecting the upper FBARs. The FACT provides impedance transformation, can linking single-ended circuitry with balanced circuitry or vice versa and electrically isolates primary and secondary. Some embodiments are additionally electrically balanced.