The general approach for calculation and analyzing frequency and field impedance dependencies of BAW composite resonator structures with parametrically exited layers is developed in this paper. The BAW resonator consisting of two piezoelectric layers was considered. The first dielectric layer was the electric input transducer of the structure and was connected with the source of signal frequency. The second one was a piezoelectric parametric layer placed in alternating uniform electric field of frequency. Different mechanisms of non-linearity in parametric piezoelectric layers are analyzed. The acoustic wave propagation in parametric layers is accompanied by the electric field wave and electron density wave of frequency. Parametrically exited composite resonator structures may serve as a source of electromagnetic oscillations.