Nowadays, Radiofrequency devices are essential for the emerging new technologies. The implementation of the new incoming wireless standards (5G, IEEE 802.11ax...) and the Internet of Things is demanding the use of acoustic technologies for filter design. This allows achieving best user experience with all the technologies working together in one portable handset: Bluetooth, 2G, 3G, 4G and the future 5G, among many others. Filters, oscillators, amplifiers and other components used in the transducer chain are fabricated with microwave resonators. Acoustic technology is the most used for resonators design, allowing miniaturization of the devices and making suitable to integrate different transducer chains in a single chip. There are two main types of electro-acoustic resonators: Bulk Acoustic Wave (BAW) and Surface Acoustic Wave (SAW). The difference between these two technologies is how the acoustic wave is propagated along the resonator. This thesis is focused in BAW resonators. BAW technology has the advantage of miniaturization, power handling, high frequency selectivity and low insertion losses. The main disadvantage is their nonlinear behavior. As the regulations and standards are demanding higher requirements and higher linearity, current acoustic devices could generate harmonics and intermodulation products that may fall at the frequency band of the receiver. The aim of this bachelor's degree thesis is the study of the nonlinear problem in BAW resonators through the implementation of nonlinear equations in new circuital models.