The present invention provides a
bulk acoustic wave filter, a design method, a manufacturing method and a
communication device, comprising: using a series thin film
bulk acoustic wave resonator and a parallel thin film
bulk acoustic wave resonator to build a bulk
acoustic wave filter with a ladder topology structure, the series thin film bulk
acoustic wave resonator and the parallel thin film bulk
acoustic wave resonator both include a functional layer and a frame structure with a protrusion, wherein the functional layer includes a lower
electrode, a piezoelectric layer, and an upper
electrode; simulating to obtain a
frequency response curve of the bulk acoustic wave filter, identifying the frequency range of a parasitic
passband caused by the protrusions of the frame structure in the series thin film bulk acoustic wave resonator and the parallel thin film bulk acoustic wave resonator at a
low frequency of the
passband of the bulk acoustic wave filter; designing the parasitic
resonance frequency of the series thin film bulk acoustic wave resonator to be lower than the parasitic
resonance frequency of the parallel thin film bulk acoustic wave resonator at the frequency range corresponding to the parasitic
passband, thereby forming a parasitic
stopband replacing the parasitic passband at the frequency range of the parasitic passband.