Abstract: A bulk acoustic wave resonator comprising a substrate, a Bragg reflector, a top and a bottom electrode and a piezoelectric layer with means for suppression of the pass-band ripples in a bulk acoustic wave filter. The means for absorbing or scattering the spurious modes are a roughened rear side of the substrate, an absorbing layer disposed on the rear side of the substrate and/or an absorbing layer disposed on the front side of the substrate.

Abstract: A thin-film bulk acoustic wave (BAW) resonator, such as SBAR or FBAR, for use in RF selectivity filters operating at frequencies of the order of 1 GHz. The BAW resonator comprises a piezoelectric layer (14) having first and second surfaces on opposing sides, a first electrode (16) extending over the first surface, and a second electrode (12) extending over the second surface, the extent of the area of overlap (R1) of the first and second electrodes determining the region of excitation of the fundamental thickness extensional (TE) mode of the resonator. The insertion loss to the resonator is reduced by providing a dielectric material (18) in the same layer as the first electrode (16) and surrounding that electrode. The material constituting the dielectric material (18) has a different mass, typically between 5% and 15%, from the material comprising the first electrode (16) it surrounds. The mass of the dielectric material (18) can be lower or higher than the mass of the first electrode (16).

Abstract: A thin-film bulk acoustic wave (BAW) resonator, such as SBAR or FBAR, for use in RF selectivity filters operating at frequencies of the order of 1 GHz. The BAW resonator comprises a piezoelectric layer (14) having first and second surfaces on opposing sides, a first electrode (16) extending over the first surface, and a second electrode (12) extending over the second surface, the extent of the area of overlap (R1) of the first and second electrodes determining the region of excitation of the fundamental thickness extensional (TE) mode of the resonator. The insertion loss to the resonator is reduced by providing a dielectric material (18) in the same layer as the first electrode (16) and surrounding that electrode. The material constituting the dielectric material (18) has a different mass, typically between 5% and 15 %, from the material comprising the first electrode (16) it surrounds. The mass of the dielectric material (18) can be lower or higher than the mass of the first electrode (16).

Abstract: An electro-acoustic resonator (1, 8, 17) of the membrane or FBAR type (1) or the solidly-mounted or SBAR type (8), with electrodes comprising a single conducting layer or multiple conducting layers, i.e. sandwich construction (17) with an optimum coupling factor kr and thus an improved filter bandwidth. The optimum coupling factor kr is achieved by the arrangement that the top electrode (6, 15, 25) is thinner than the bottom electrode (4, 13, 23). The coupling factor is independent of the resonator's layout defined by the mask.

Abstract: A ladder filter comprising a plurality of bulk acoustic wave resonators, the resonators comprising a plurality of series resonators series resonators in series between an input terminal and an output terminal of the filter, and one or more shunt resonators each connected between a junction between two series resonators and a common terminal, the series resonators comprising an input series resonator connected to the input terminal and an output series resonator connected to the output terminal, and wherein the shunt resonators are designed to satisfy: a unity aspect ratio and wherein the series resonators are designed to satisfy an aspect ratio different from unity. The aspect ratio is defined as the ratio of length to width of the resonator.

Abstract: In order to provide a resonator structure (100) in particular a bulk-acoustic-wave (BAW) resonator, such as a film BAW resonator (FBAR) or a solidly-mounted BAW resonator (SBAR), comprising at least one substrate (10); at least one reflector layer (20) applied or deposited on the substrate (10); at least one bottom electrode layer (30), in particular bottom electrode, applied or deposited on the reflector layer (20); at least one piezoelectric layer (40), in particular C-axis normal piezoelectric layer, applied or deposited on the bottom electrode layer (30); at least one top electrode layer (50), in particular top electrode, applied or deposited on the bottom electrode layer (30) and/or on the piezoelectric layer (40) such that the piezoelectric layer (40) is in between the bottom electrode layer (30) and the top electrode layer (50), it is proposed that at least one dielectric layer (63, 65) applied or deposited in and/or on at least one space in at least one region of non-overlap between the bottom electro

Abstract: In order to provide a resonator structure (100) in particular a bulk-acoustic-wave (BAW) resonator, such as a film BAW resonator (FBAR) or a solidly-mounted BAW resonator (SBAR), comprising at least one substrate (10); at least one reflector layer (20) applied or deposited on the substrate (10); at least one bottom electrode layer (30), in particular bottom electrode, applied or deposited on the reflector layer (20); at least one piezoelectric layer (40), in particular C-axis normal piezoelectric layer, applied or deposited on the bottom electrode layer (30); at least one top electrode layer (50), in particular top electrode, applied or deposited on the bottom electrode layer (30) and/or on the piezoelectric layer (40) such that the piezoelectric layer (40) is in between the bottom electrode layer (30) and the top electrode layer (50), it is proposed that at least one dielectric layer (63, 65) applied or deposited in and/or on at least one space in at least one region of non-overlap between the bottom electro

Abstract: A filter structure, comprising a first signal line, a second signal line, a third signal line and a fourth signal line, said first and third signal lines defining an input port and said second and fourth signal lines defining an output port of a section of said filter structure, said section being defined by a first bulk acoustic wave resonator (A) which is connected between said first signal line and said second signal line, a second bulk acoustic wave resonator (G) which is connected between said third signal line and said fourth signal line, a third bulk acoustic wave resonator (C) which is connected between said first signal line and said fourth signal line, and a fourth bulk acoustic wave resonator (E) which is connected between said second signal line and said third signal line; is characterized in that a frequency pulling factor defined d of at least one of said acoustic wave resonators is non-zero, said frequency pulling factor d being defined by for first and second bulk acoustic wave resonators havi

Abstract: The invention relates to a filter device equipped with at least one bulk acoustic wave resonator, which comprises a resonator unit and a reflection element (2) comprising several layers (6, 7, 8). The layers (6, 7, 8) each comprise a mixture of at least two materials. Within each layer (6, 7, 8), the composition of the mixture varies continuously and periodically relative to the layer thickness.

Abstract: The invention relates to a filter device equipped with at least one bulk acoustic wave resonator, which comprises a resonator unit and a reflection unit. The resonator unit comprises a first (3) and a second electrode (5) together with a textured piezoelectric layer (4) between the first (3) and second (5) electrodes.

Abstract: The invention relates to a filter device equipped with at least one bulk acoustic wave resonator, which comprises a resonator unit and a reflection unit. The resonator unit comprises a first (3) and a second electrode (5) together with a textured piezoelectric layer (4) between the first (3) and second (5) electrodes.

Abstract: The invention describes a tunable filter arrangement with at least two resonators which are coupled to one another and of which at least one is connected to a capacitor with tunable capacitance. The electrical properties of the resonator, and thus the overall filter characteristic, can be changed through a change in the capacitance of the capacitor. Furthermore, a transmitter, a receiver, a mobile telephone device, and a wireless data transmission system comprising such a filter arrangement are disclosed, as is a tunable bulk acoustic wave resonator.

Abstract: The invention describes a tunable filter arrangement with a plurality of resonators which are coupled to one another and of which there is at least one which comprises a piezoelectric component made of a ferroelectric material and to which a DC voltage source is connected. The application of a DC voltage to the resonator renders it possible to change its electrical properties and thus the overall filter characteristic. Furthermore, a transmitter, a receiver device, and a mobile telephone device with such a filter arrangement are disclosed, aswell as a tunable bulk acoustic wave resonator.

Abstract: The invention relates to an arrangement with two piezoelectric layers (2, 5) and to a method of operating the arrangement as a filter. One (2) of the two piezoelectric layers (2, 5) in the arrangement is situated between an electrode (3) and a middle electrode (4), and the other one (5) of the two piezoelectric layers (2, 5) is positioned between another electrode (6) and said middle electrode (4) such that a bulk acoustic wave resonator is formed. The one and the other electrode (3, 6) and the middle electrode (4) are connected to circuitry means for applying high-frequency signals to at least one of the two piezoelectric layers (2, 5) such that the bulk acoustic wave resonator has at least one resonance frequency when the circuitry means are in one switching state, and that the bulk acoustic wave resonator has at least one other resonance frequency different from the at least one resonance frequency when the circuitry means are in another switching state.

Abstract: The invention describes a tunable filter arrangement with at least two resonators which are coupled to one another and of which at least one is connected to a capacitor with tunable capacitance. The electrical properties of the resonator, and thus the overall filter characteristic, can be changed through a change in the capacitance of the capacitor.

Abstract: The invention describes a tunable filter arrangement with a plurality of resonators which are coupled to one another and of which there is at least one which comprises a piezoelectric component made of a ferroelectric material and to which a DC voltage source is connected. The application of a DC voltage to the resonator renders it possible to change its electrical properties and thus the overall filter characteristic.