Trw Limited

Drew Cushman

Jay D Crawford

Robert Bruce Stokes

Alvin M Kong

Edward M Garber

Jay D Cushman

A semiconductor bulk acoustic resonator (SBAR) with improved passband insertion loss and phase performance characteristics making it suitable for use in a wider variety of narrowband filtering applications. The SBAR is configured to suppress lateral propagating acoustical wave mode. The lateral acoustical wave modes are controlled by varying the lateral dimension of the resonator electrodes and or utilizing a viscous acoustic damping material, such as a viscoelastic material, such as polyimide, along at least~a portion of the perimeter of the electrodes to attenuate reflections of the lateral acoustic modes at the electrode edges back into the electrode region.

Semiconductor bulk acoustic resonator with suppressed lateral modes

A semiconductor bulk acoustic resonator (SBAR) with improved passband insertion loss and phase performance characteristics is suitable for use in a wide variety of narrowband filtering applications. The SBAR is configured to suppress lateral propagating acoustical wave modes. The lateral acoustical wave modes are controlled by varying the lateral dimension of the resonator electrodes and or utilizing a viscous acoustic damping material, such as a viscoelastic material, such as polyimide, applied along at least a portion of the perimeter of the electrodes to attenuate reflections of the lateral acoustic modes at the electrode edges back into the electrode region.

Lateral mode suppression in semiconductor bulk acoustic resonator (SBAR)

A low frequency mechanical resonator that resonates at relatively low frequencies and can be fabricated as part of an integrated circuit. The resonator includes a piezoelectric structure having a top piezoelectric layer and a bottom piezoelectric layer positioned over a recessed area in a substrate. A top input electrode is positioned on the top surface of the top piezoelectric layer, a middle shield electrode is positioned between the piezoelectric layers, and a bottom output electrode is positioned on the bottom surface of the bottom piezoelectric layer adjacent the recessed area. By applying an appropriate alternating current to the top electrode, the top piezoelectric layer is alternately contracted and expanded. Because the top piezoelectric layer is secured to the bottom piezoelectric layer, the piezoelectric structure will flex up and down in order to relieve stress within the structure. The flexing of the piezoelectric structure causes flexural waves within the piezoelectric structure which resonate at a particular frequency depending on the membrane material, membrane thickness, and the width of the recessed area. The top and bottom electrodes can be replaced with interdigital transducers in order to select particular higher order flexural resonances for higher resonant frequencies.

Low frequency mechanical resonator

Disclosed is a thin film voltage-tuned semiconductor bulk acoustic resonator (SBAR). A piezoelectric film is positioned between a first electrode and a second electrode and positioned adjacent a semiconductor substrate containing a via hole. A variable voltage source applies a DC bias voltage to the electrodes which causes an electric field to be created between the electrodes within the piezoelectric film. The resulting electric field causes the piezoelectric film to resonate at a frequency different than its unbiased resonant frequency. By adjusting the variable voltage source to change the DC bias voltage, the resonant frequency from the thin film semiconductor bulk acoustic resonator (SBAR) can be varied.

Thin film voltage-tuned semiconductor bulk acoustic resonator (SBAR)

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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Lomita, CA, United States of America

Drew Cushman