Monolithic multipole filters made of thin film stacked crystal filters
First Claim
1. A multipole stacked crystal filter comprising:
- a plurality of cascaded 2-port semiconductor bulk acoustic resonator (SBAR) stacked crystal filters (SCFs) electrically connected on a common semiconductor substrate, each 2-port SBAR SCF including at least two piezoelectric layers and three electrodes, a first one of the electrodes being positioned in contact with a first surface of a first piezoelectric layer, a second one of the electrodes being positioned in contact with a second surface of the first piezoelectric layer and a first surface of a second piezoelectric layer, and a third one of the electrodes being positioned in contact with a second surface of the second piezoelectric layer opposite to the first surface of the second piezoelectric layer, wherein a respective third one of the electrodes of a particular 2-port SBAR SCF is connected to a respective first one of the electrodes of a next 2-port SBAR SCF of the cascade of SBAR SCFs; and
at least one inductor electrically connected in shunt between a respective third one of the electrodes of a corresponding 2-port SBAR SCF and ground.
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Abstract
This invention discloses a monolithic multipole stacked crystal filter comprised of a series of cascaded 2-port semiconductor bulk acoustic resonator stacked crystal filters electrically cascaded and a shunt inductor connected between each of the 2-port filters. Each of the 2-port filters including a first and second piezoelectric layer, typically aluminum nitride. A first input electrode is positioned on a top surface of one of the piezoelectric layers and a second output electrode is positioned on a bottom surface of the other of the piezoelectric layers. A ground electrode is positioned between the piezoelectric layers. In this regard, the piezoelectric layers will resonate at a resonant frequency and provide bandpass filter characteristics. The complete monolithic multipole filter provides control of the passband shape which yields highly desirable filter characteristics.
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Citations
18 Claims
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1. A multipole stacked crystal filter comprising:
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a plurality of cascaded 2-port semiconductor bulk acoustic resonator (SBAR) stacked crystal filters (SCFs) electrically connected on a common semiconductor substrate, each 2-port SBAR SCF including at least two piezoelectric layers and three electrodes, a first one of the electrodes being positioned in contact with a first surface of a first piezoelectric layer, a second one of the electrodes being positioned in contact with a second surface of the first piezoelectric layer and a first surface of a second piezoelectric layer, and a third one of the electrodes being positioned in contact with a second surface of the second piezoelectric layer opposite to the first surface of the second piezoelectric layer, wherein a respective third one of the electrodes of a particular 2-port SBAR SCF is connected to a respective first one of the electrodes of a next 2-port SBAR SCF of the cascade of SBAR SCFs; and at least one inductor electrically connected in shunt between a respective third one of the electrodes of a corresponding 2-port SBAR SCF and ground. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of filtering a broad band frequency signal comprising the steps of:
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providing a series of 2-port semiconductor bulk acoustic resonator (SBAR) stacked crystal filters (SCFs) electrically connected in a cascaded fashion, wherein each SBAR SCF includes at least two piezoelectric layers and three electrodes where a first electrode is in contact with a first surface of a first piezoelectric layer, a second electrode is in contact with a second surface of the first piezoelectric layer and a first surface of a second piezoelectric layer, and a third electrode is in contact with a second surface of the second piezoelectric layer opposite to the first surface of the second piezoelectric layer, wherein the respective third electrode of a particular SBAR SCF is connected to the respective first electrode of a next SBAR SCF of the series of SBAR SCFs; providing at least one inductor electrically connected to a third electrode of a respective SBAR SCF and ground so as to be respectively in shunt between at least two of the 2-port SBAR SCFs; and applying the broad band frequency signal to a first SBAR SCF in the series of 2-port SBAR SCFs and outputting a narrow band frequency from a last SBAR SCF in the series of 2-port SBAR SCFs. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A multipole stacked crystal filter comprising:
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a plurality of cascaded 2-port semiconductor bulk acoustic resonator (SBAR) stacked crystal filters (SCFs) electrically connected on a common semiconductor substrate, each 2-port SBAR SCF including two piezoelectric layers and three electrodes, an input electrode being positioned in contact with a first surface of a first piezoelectric layer, a ground electrode being positioned in contact with a second surface of the first piezoelectric layer and a first surface of a second piezoelectric layer, and an output electrode being positioned in contact with a second surface of the second piezoelectric layer opposite to the first surface of the second piezoelectric layer, wherein the respective output electrode of one SBAR SCF is connected to the input electrode of a next SBAR; and at least one inductor connected in shunt between the output electrode of an SBAR SCF and ground for each 2-port SBAR SCF, wherein the 2-port SBAR SCFs and the inductors provide a desired filter passband shape. - View Dependent Claims (18)
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Specification