3. Resonator sizing

In practice, a volume wave resonator does not consist of a single piezoelectric layer with infinitely fine metallizations. As shown in figure 10 , it is supplemented by metal electrodes of finite thickness, environmental protection coatings, and a whole range of additional layers designed to individualize the frequencies of certain resonators in relation to others. In addition, since the resonator must be acoustically isolated from the substrate on which it is produced, specific structures are formed for this purpose. This makes it possible to distinguish between two types of bulk wave resonator: membrane resonators (called Film Bulk Acoustic Resonator, or FBAR) (figure