Film acoustically-coupled transformer with increased common mode rejection
First Claim
1. A film acoustically-coupled transformer (FACT), comprising:
- a first decoupled stacked bulk acoustic resonator (DSBAR) and a second DSBAR, each DSBAR comprising;
a lower film bulk acoustic resonator (FBAR) and an upper FBAR, the upper FBAR stacked atop the lower FBAR, each FBAR comprising opposed planar electrodes and a piezoelectric element between the electrodes, andan acoustic decoupler between the FBARs;
a first electrical circuit interconnecting the lower FBARs; and
a second electrical circuit interconnecting the upper FBARs;
in which;
in at least one of the DSBARs, the acoustic decoupler, one of the electrodes of the lower FBAR adjacent the acoustic decoupler and one of the electrodes of the upper FBAR adjacent the acoustic decoupler constitute a parasitic capacitor; and
the FACT additionally comprises an inductor electrically connected in parallel with the parasitic capacitor.
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Abstract
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.
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Citations
22 Claims
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1. A film acoustically-coupled transformer (FACT), comprising:
- a first decoupled stacked bulk acoustic resonator (DSBAR) and a second DSBAR, each DSBAR comprising;
a lower film bulk acoustic resonator (FBAR) and an upper FBAR, the upper FBAR stacked atop the lower FBAR, each FBAR comprising opposed planar electrodes and a piezoelectric element between the electrodes, and an acoustic decoupler between the FBARs; a first electrical circuit interconnecting the lower FBARs; and a second electrical circuit interconnecting the upper FBARs;
in which;in at least one of the DSBARs, the acoustic decoupler, one of the electrodes of the lower FBAR adjacent the acoustic decoupler and one of the electrodes of the upper FBAR adjacent the acoustic decoupler constitute a parasitic capacitor; and the FACT additionally comprises an inductor electrically connected in parallel with the parasitic capacitor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
- a first decoupled stacked bulk acoustic resonator (DSBAR) and a second DSBAR, each DSBAR comprising;
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21. A film acoustically-coupled transformer (FACT) having a pass band, the FACT comprising:
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a first decoupled stacked bulk acoustic resonator (DSBAR) and a second DSBAR, each DSBAR comprising; a lower film bulk acoustic resonator (FBAR) and an upper FBAR, the upper FBAR stacked atop the lower FBAR, each FBAR comprising opposed planar electrodes and a piezoelectric element between the electrodes, and an acoustic decoupler between the FBARs, a first electrical circuit interconnecting the lower FBARs; and a second electrical circuit interconnecting the upper FBARs;
in which;in at least one of the DSBARs, the acoustic decoupler, one of the electrodes of the lower FBAR adjacent the acoustic decoupler and one of the electrodes of the upper FBAR adjacent the acoustic decoupler constitute a parasitic capacitor; and the FACT additionally comprises means for forming with the parasitic capacitor a parallel resonant circuit having a resonant frequency in the pass band. - View Dependent Claims (22)
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Specification