Avago Technologies Wireless IP (singapore) Pte. Ltd.

Avago Technologies Wireless Ip, Pte. Ltd.

Naghmeh Sarkeshik

John Dwight Larson, Iii

Stephen Ellis

The film acoustically-coupled transformer (FACT) has a first and second decoupled stacked bulk acoustic resonators (DSBARs). Each DSBAR has a lower film bulk acoustic resonator (FBAR), an upper FBAR atop the lower FBAR, and an acoustic decoupler between them FBARs. Each FBAR has opposed planar electrodes and a piezoelectric element between the electrodes. A first electrical circuit interconnects the lowers FBAR of the first DSBAR and the second DSBAR. A second electrical circuit interconnects the upper FBARs of the first DSBAR and the second DSBAR. In at least one of the DSBARs, the acoustic decoupler and one electrode of the each of the lower FBAR and the upper FBAR adjacent the acoustic decoupler constitute a parasitic capacitor. The FACT additionally has an inductor electrically connected in parallel with the parasitic capacitor. The inductor increases the common-mode rejection ratio of the FACT.

Film acoustically-coupled transformer with increased common mode rejection

The film acoustically-coupled transformer (FACT) has decoupled stacked bulk acoustic resonators (DSBARs), a first electrical circuit and a second electrical circuit. Each of the DSBARs has a lower film bulk acoustic resonator (FBAR), an upper FBAR and an acoustic decoupler. The upper FBAR is stacked on the lower FBAR and the acoustic decoupler is located between the FBARs. Each FBAR has opposed planar electrodes and a piezoelectric element between the electrodes. The first electrical circuit interconnects the lower FBARs. The second electrical circuit interconnects the upper FBARs. The FBARs of one of the DSBARs differ in electrical impedance from the FBARs of another of the DSBARs. The FACT has an impedance transformation ratio greater than 1:m, where m is the number of DSBARs. The actual impedance transformation ratio depends on the ratio of the impedances of the FBARs.

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Cupertino, CA, United States of America

Naghmeh Sarkeshik