Impedance transforming bulk acoustic wave baluns
First Claim
1. A bulk acoustic wave (BAW) device comprising:
- a stacked bulk acoustic wave resonator (SBAR) comprising an acoustic decoupler between first and second film bulk acoustic resonators (FBARs),the first FBAR being resonant at a resonant frequency and comprising first and second planar electrodes abutting opposite sides of a first resonator volume free of intervening electrodes and containing piezoelectric material disposed for acoustic vibrations parallel to a propagation axis normal to the first and second electrodes, the first FBAR having a first electrical impedance parallel to the propagation axis,the second FBAR being resonant at the resonant frequency and comprising third and fourth planar electrodes abutting opposite sides of a second resonator volume free of intervening electrodes and containing piezoelectric material disposed for acoustic vibrations parallel to the propagation axis, the second FBAR having a second electrical impedance parallel to the propagation axis and different from the first electrical impedance,wherein the first resonator volume has a first thickness dimension between the first and second planar electrodes parallel to the propagation axis and the second resonator volume has a second thickness dimension between the third and fourth planar electrodes parallel to the propagation axis, the second thickness dimension being different from the first thickness dimension, andwherein each of the first and second planar electrodes has a thickness parallel to the propagation axis that is different from a thickness of each of the third and fourth planar electrodes parallel to the propagation axis, compensating for the difference between the first and second thickness dimensions, such that the first and second FBARs have substantially the same overall acoustic thickness.
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Abstract
A bulk acoustic wave device includes an acoustic decoupler between first and second film bulk acoustic resonators (FBARs). The first FBAR is resonant at a resonant frequency of the device and includes first and second planar electrodes abutting opposite sides of a first resonator volume free of any intervening electrodes and containing piezoelectric material disposed for acoustic vibrations parallel to a propagation axis normal to the first and second electrodes. The first FBAR has a first electrical impedance parallel to the propagation axis. The second FBAR is resonant at the resonant frequency and includes third and fourth planar electrodes abutting opposite sides of a second resonator volume free of any intervening electrodes and containing piezoelectric material disposed for acoustic vibrations parallel to the propagation axis. The second FBAR has a second electrical impedance parallel to the propagation axis and different from the first electrical impedance.
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Citations
19 Claims
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1. A bulk acoustic wave (BAW) device comprising:
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a stacked bulk acoustic wave resonator (SBAR) comprising an acoustic decoupler between first and second film bulk acoustic resonators (FBARs), the first FBAR being resonant at a resonant frequency and comprising first and second planar electrodes abutting opposite sides of a first resonator volume free of intervening electrodes and containing piezoelectric material disposed for acoustic vibrations parallel to a propagation axis normal to the first and second electrodes, the first FBAR having a first electrical impedance parallel to the propagation axis, the second FBAR being resonant at the resonant frequency and comprising third and fourth planar electrodes abutting opposite sides of a second resonator volume free of intervening electrodes and containing piezoelectric material disposed for acoustic vibrations parallel to the propagation axis, the second FBAR having a second electrical impedance parallel to the propagation axis and different from the first electrical impedance, wherein the first resonator volume has a first thickness dimension between the first and second planar electrodes parallel to the propagation axis and the second resonator volume has a second thickness dimension between the third and fourth planar electrodes parallel to the propagation axis, the second thickness dimension being different from the first thickness dimension, and wherein each of the first and second planar electrodes has a thickness parallel to the propagation axis that is different from a thickness of each of the third and fourth planar electrodes parallel to the propagation axis, compensating for the difference between the first and second thickness dimensions, such that the first and second FBARs have substantially the same overall acoustic thickness. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A bulk acoustic wave (BAW) device, comprising:
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a first stacked bulk acoustic wave resonator (SBAR) comprising a first acoustic decoupler between first and second film bulk acoustic resonators (FBARs), the first FBAR being resonant at a resonant frequency and comprising first and second planar electrodes abutting opposite sides of a first resonator volume free of intervening electrodes and containing piezoelectric material disposed for acoustic vibrations parallel to a propagation axis normal to the first and second electrodes, the first FBAR having a first electrical impedance parallel to the propagation axis, and the second FBAR being resonant at the resonant frequency and comprising third and fourth planar electrodes abutting opposite sides of a second resonator volume free of intervening electrodes and containing piezoelectric material disposed for acoustic vibrations parallel to the propagation axis, the second FBAR having a second electrical impedance parallel to the propagation axis and different from the first electrical impedance; and a second SBAR electrically coupled to the first SBAR and comprising a second acoustic decoupler between third and fourth FBARs, the third FBAR being resonant at the resonant frequency and comprising fifth and sixth planar electrodes abutting opposite sides of a third resonator volume free of intervening electrodes and containing piezoelectric material disposed for acoustic vibrations parallel to the propagation axis, the third FBAR having a third electrical impedance parallel to the propagation axis, and the fourth FBAR being resonant at the resonant frequency and comprising seventh and eighth planar electrodes abutting opposite sides of a fourth resonator volume free of intervening electrodes and containing piezoelectric material disposed for acoustic vibrations parallel to the propagation axis, the fourth FBAR having a fourth electrical impedance parallel to the propagation axis and different from the third electrical impedance, wherein the first resonator volume has a first thickness dimension between the first and second planar electrodes parallel to the propagation axis and the second resonator volume has a second thickness dimension between the third and fourth planar electrodes parallel to the propagation axis, the second thickness dimension being different from the first thickness dimension, and wherein the first electrode is electrically coupled to the fifth electrode, the second electrode is electrically coupled to a single-ended signal port, the fourth electrode is electrically coupled to a first differential signal port, the eighth electrode is electrically coupled to a second differential signal port, and the third, sixth and seventh electrodes are electrically coupled to a device ground.
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19. An impedance transforming balun, comprising:
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a first film bulk acoustic resonator (FBAR) resonant at a resonant frequency and having a first electrical impedance, the first FBAR comprising a first planar electrode, a second planar electrode, and a first resonator volume between the first and second planar electrodes, the first resonator volume having a first thickness dimension between the first and second planar electrodes and comprising piezoelectric material arranged for acoustic vibrations parallel to a propagation axis normal to the first and second planar electrodes; a second FBAR resonant at the resonant frequency and having a second electrical impedance different from the first electrical impedance, the second FBAR comprising a third planar electrode, a fourth planar electrode, and a second resonator volume between the third and fourth planar electrodes, the second resonator volume having a second thickness dimension between the third and fourth planar electrodes and comprising piezoelectric material arranged for acoustic vibrations parallel to the propagation axis, the second thickness dimension being different from the first thickness dimension; and an acoustic decoupler between the first FBAR and the second FBAR, wherein the first and second planar electrodes have a thickness parallel to the propagation axis that is different from a thickness of the third and fourth planar electrodes parallel to the propagation axis, compensating for the difference between the first and second thickness dimensions, so that the second FBAR has substantially the same overall acoustic thickness as the first FBAR parallel to the propagation axis.
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Specification