Transversely-excited film bulk acoustic resonator filters with sub-resonators having different mark and pitch
AssigneeMurata Manufacturing Co., Ltd.
InventorsDouglas Jachowski, Greg Dyer
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Abstract
Radio frequency filters are disclosed. A bandpass filter is discloses that includes one first bulk acoustic resonator on a first chip including a first piezoelectric layer having an LN-equivalent thickness less than or equal to 535 nm; a second bulk acoustic resonator on a second chip including a second piezoelectric layer having a thickness greater than the LN-equivalent thickness of the piezoelectric layer on the first chip; and a circuit card coupled to the first chip and the second chip and that electrically connects the first chip to the second chip.
Claims20
A bandpass filter comprising:
- at least one first bulk acoustic resonator on a first chip comprising a first piezoelectric layer comprising lithium niobate (LN) and having an LN-equivalent thickness teqa less than or equal to 535 nm;
- at least one second bulk acoustic resonator on a second chip comprising a second piezoelectric layer having a thickness greater than the LN-equivalent thickness teqa of the piezoelectric layer on the first chip;
- and
- a circuit card coupled to the first chip and the second chip and that electrically connects the first chip to the second chip,
- wherein the LN-equivalent thickness teqa of the first piezoelectric layer is defined by the formula:
- teqa
- ≈
- tp
- +
- ka
-
- (
- tfsd
- )
- ,
- wherein tp is a thickness of the first piezoelectric layer, tfsd is a thickness of a dielectric layer at the at least one first bulk acoustic resonator, ka is a constant for the at least one first bulk acoustic resonator, and ka=0.45.
A split-ladder filter comprising:
- at least one first bulk acoustic resonator on a first chip comprising a first piezoelectric layer comprising lithium niobate (LN) and having an LN-equivalent thickness teqa less than or equal to 535 nm, wherein the at least one first bulk acoustic resonator comprises at least two first sub-resonators having approximately a same aperture and length, wherein the at least two first sub-resonators are connected in parallel and have a first pitch;
- at least one second bulk acoustic resonator on a second chip comprising a second piezoelectric layer having a thickness greater than the LN-equivalent thickness teqa of the first piezoelectric layer on the first chip, wherein the at least one second bulk acoustic resonator comprises at least two second sub-resonators having approximately a same aperture and length, wherein the at least two second sub-resonators are connected in parallel and have a second pitch;
- and
- a circuit card coupled to the first chip and the second chip and that electrically connects the first chip to the second chip,
- wherein the LN-equivalent thickness teqa of the first piezoelectric layer is defined by the formula:
- teqa
- ≈
- tp
- +
- ka
-
- (
- tfsd
- )
- ,
- wherein tp is a thickness of the first piezoelectric layer, tfsd is a thickness of a dielectric layer at the at least one first bulk acoustic resonator, and ka is a constant for the at least one first bulk acoustic resonator.
Dependencies are inferred from the claim text.