Monolithic thin-film piezoelectric filters
First Claim
1. A microelectromechanical acoustic filter apparatus comprising:
- a substrate; and
a resonant structure released from and supported by the substrate that comprises;
a thin-film piezoelectric layer disposed between a lower electrode and a plurality of electrically isolated upper electrodes patterned to excite a plurality of acoustically-coupled resonance modes of the resonant structure, wherein the resonant structure is connected by way of support beams to the substrate;
wherein the order of the frequency response of the filter is greater than two.
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Accused Products
Abstract
Disclosed are exemplary monolithic acoustically coupled thin film piezoelectric-on-substrate filters that operate in a wide frequency range. The monolithic thin-film-piezoelectric acoustic filters includes a resonant structure that is released from and supported by a substrate that comprises a thin-film piezoelectric layer disposed between a lower electrode and a plurality of electrically isolated upper electrodes. Second order narrowband filters are realized by utilizing coupled resonance modes of a single microstructure. Narrow-bandwidth filters are disclosed that are suitable for channel-select applications in IF and RF bands. Filter Q values of 800 at 250 MHz, 470 at 360 MHz, and 400 at 3.5 GHz for small footprint second-order filters are disclosed. The measured power handling of these devices is high due to the use of high energy density structural material, showing a 0.2 dB compression point of >15 dBm at 360 MHz.
20 Citations
18 Claims
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1. A microelectromechanical acoustic filter apparatus comprising:
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a substrate; and a resonant structure released from and supported by the substrate that comprises; a thin-film piezoelectric layer disposed between a lower electrode and a plurality of electrically isolated upper electrodes patterned to excite a plurality of acoustically-coupled resonance modes of the resonant structure, wherein the resonant structure is connected by way of support beams to the substrate; wherein the order of the frequency response of the filter is greater than two. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. Microelectromechanical acoustic filter apparatus comprising:
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a substrate comprising a silicon-on-insulator (SOI) substrate; and a resonant structure released from and supported by the substrate that comprises; a thin-film piezoelectric layer disposed between a lower electrode and a plurality of electrically isolated upper electrodes that comprise interdigitated fingers to provide a second order filter that operates in fundamental or high-order thickness-extensional mode; and a portion of the silicon device layer of the SOI substrate. - View Dependent Claims (11, 12, 13)
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14. A microelectromechanical acoustic filter apparatus comprising:
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a substrate; and a resonant structure released from and supported by the substrate that comprises; a thin-film piezoelectric layer disposed between a lower electrode and a plurality of electrically isolated upper electrodes that comprise two sets of spaced apart opposed electrically connected fingers to provide a second order filter that operates in lateral, fundamental or high-order width- or length-extensional, resonance mode, the plurality of electrically isolated upper electrodes patterned to excite a plurality of acoustically-coupled resonance modes of the resonant structure; wherein the substrate comprises a silicon-on-insulator (SOI) substrate and wherein the resonant structure further comprises a portion of the silicon device layer of the SOI substrate. - View Dependent Claims (15, 16, 17, 18)
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Specification