Vtt Technical Research Centre of Finland Ltd

Teknologian Tutkimuskeskus Vtt Oy

Tapani Makkonen

Tuomas Pensala

Markku Antero Ylilammi

James Dekker

The device includes an acoustic wave filter element, and a first resonator. The acoustic wave filter element includes interdigitated input electrodes and output electrodes located on a top surface of a piezoelectric layer and a counter-electrode on a bottom surface of the piezoelectric layer. The acoustic wave filter element provides a response with a sideband at a sideband frequency range. The first resonator includes a first resonator electrode on the top surface of the piezoelectric layer and a first resonator counter-electrode on the bottom surface of the piezoelectric layer. The first resonator has a first notch in resonator impedance at a first frequency. The first resonance frequency is tuned to fall within the sideband frequency range to suppress the sideband by depositing a first mass load on top of the first resonator electrode to reduce the first resonance frequency, or partly removing the first resonator electrode to increase the first resonance frequency.

Loaded resonators for adjusting frequency response of acoustic wave resonators

An acoustic wave filter device with two-stage acoustic wave filters is provided. Each of the two stages includes a respective acoustic wave filter element. A first acoustic wave filter element () includes a first input electrode (), a first output electrode (), and a first counter electrode (). The first input electrode and the first output electrode are located on a top surface of piezoelectric layer (), and the first counter electrode is located on a bottom surface of the piezoelectric layer. A second acoustic wave filter element () includes a second input electrode (), a second output electrode (), and a second counter electrode (). The second input electrode and the second output electrode are located on the top surface of the piezoelectric layer, and the second counter electrode is located on a bottom surface of the piezoelectric layer. The two acoustic wave filter elements are connected in series through a common floating electrode ().

Two-stage lateral bulk acoustic wave filter with capacitive coupling of counter electrode

Acoustic wave devices are disclosed. The devices include a substrate, a bi-layer reflector and an acoustic wave resonator. The bi-electric reflector is above the substrate and includes a first layer that has a first acoustic impedance, and a second layer that has a second acoustic impedance lower than the first acoustic impedance. The first layer has a first surface that includes a floating region that provides a ceiling of a cavity. The second layer is on top of the floating region of the first layer. The acoustic wave resonator is on top of the second layer of the bi-layer reflector. The acoustic wave resonator includes a piezoelectric layer, an electrode and a counter-electrode such that application of a radio frequency voltage between the electrode and the counter-electrode creates acoustic resonance waves in the piezoelectric layer.

Low loss acoustic device

An acoustic wave filter device is disclosed. The device includes an acoustic wave filter element, and a first resonator and a second resonator coupled to the acoustic wave filter element. The acoustic wave filter element includes interdigited input electrodes and output electrodes located on a top surface of a piezoelectric layer. Each of the first and the second resonators includes a top electrode on the top surface, and a bottom electrode on the bottom surface of the piezoelectric layer. At least one of each of the first and the second resonators' electrodes is electrically connected to the acoustic wave filter element. The first resonator has a first notch in resonator impedance at a first frequency. The second resonator includes a first mass loading layer on the second resonator electrode such that the second resonator has a second notch in resonator impedance at a second frequency different from the first frequency.

Loaded series resonators for adjusting frequency response of acoustic wave resonators

Acoustic wave filter devices are disclosed. A device includes a layer providing or on a topmost layer of an acoustic reflector. The intermediary layer has a first region and a second region. The first region has a first layer thickness and the second region has a second layer thickness different from the first layer thickness. The device includes a first multilayer stack on the first region and a second multilayer stack on the second region of the intermediary layer. Each of the first and the second stacks includes a piezoelectric layer on a counter electrode that is located on the respective region, an input and an output electrode. Application of a radio frequency voltage between the input electrode and the counter electrode layer of the first stack creates acoustic resonance modes in the piezoelectric layer between the input and output electrodes of the first and the second stack.

Two-stage lateral bulk acoustic wave filter

Acoustic wave filter devices is disclosed. The device includes a piezoelectric layer, an input electrode and an output electrode located on a top surface of the piezoelectric layer and physically separated from one another, and a counter electrode having a top surface connected to a bottom surface of the piezoelectric layer. The input and output electrodes each include a base and at least one extension extending from the base. The at least one extension of the input electrode extending alongside and in a generally opposite direction to and separated by a gap width from an adjacent extension of the at least one extensions of the output electrode. In some embodiments, the at least one extension of the input or output electrodes has a width that can changes from a first end of the at least one extension to a second end.

Lateral bulk acoustic wave filter

An acoustic wave filter device is disclosed. The device includes an acoustic wave filter element, and a first resonator and a second resonator coupled to the acoustic wave filter element. The acoustic wave filter element includes interdigitated input electrodes and output electrodes located on a top surface of a piezoelectric layer and an counter-electrode on the bottom surface of the piezoelectric layer. Each of the first and the second resonators includes a resonator electrode on the top surface of the piezoelectric layer and a resonator counter-electrode on the bottom surface of the piezoelectric layer. The first resonator has a first notch in resonator impedance at a first frequency. The second resonator includes a first mass loading layer on the second resonator electrode such that the second resonator has a second notch in resonator impedance at a second frequency that is different from the first frequency.

Acoustic wave filter devices are disclosed. In an embodiment, the device includes an acoustic wave resonator and a reflecting layer located below the acoustic wave resonator. The wave resonator includes an input electrode including a first electrode and a counter electrode, a piezoelectric layer sandwiched between the first electrode and the counter electrode, and an output electrode. The piezoelectric layer has a first region covered by the first or the output electrode, and a second region not covered by any of the first and the output electrode. The first region has a second order acoustic thickness-shear resonance (TS2) mode dispersion curve with a first minimum frequency, and the second region has a TS2 mode dispersion curve with a second minimum frequency. The reflecting layer's thickness is such that a difference between the first minimum frequency and the second minimum frequency is less than 2% of a filter center frequency.

Suppressing parasitic sidebands in lateral bulk acoustic wave resonators

An acoustic wave filter device is disclosed. The device includes an acoustic wave filter element, and a first resonator and a second resonator coupled to the acoustic wave filter element. The acoustic wave filter element includes interdigited input electrodes and output electrodes located on a top surface of a piezoelectric layer and an counter-electrode on the bottom surface of the piezoelectric layer. Each of the first and the second resonators includes a resonator electrode on the top surface of the piezoelectric layer and a resonator counter-electrode on the bottom surface of the piezoelectric layer. The first resonator has a first notch in resonator impedance at a first frequency. The second resonator includes a first mass loading layer on the second resonator electrode such that the second resonator has a second notch in resonator impedance at a second frequency that is different from the first frequency.

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Espoo, Finland

Tapani Makkonen