Abstract: A mirror for a piezoelectric resonator consisting of alternately arranged layers of high and low acoustic impedance is manufactured by at first producing a first layer on which a second layer is produced, so that the second layer partially covers the first layer. Then, a planarization layer is applied on the first layer and on the second layer. Subsequently, a portion of the second layer is exposed by structuring the planarization layer, wherein the portion is associated with an active region of the piezoelectric resonator. Finally, the resulting structure is planarized by removing the portions of the planarization layer remaining outside the portion.

Abstract: A circuit and method are provided for ensuring that a fingerprint sensor is started automatically when a finger is rested thereon such that a sufficiently contrasting image can be produced. A difference between a maximum and a minimum value of the sensor signals is generated wherein, if the difference is sufficiently large, indicating a sufficient contrast of an image to be produced, a normal scanning operation of the fingerprint sensor is initiated, thus ensuring that the complete fingerprint image is produced, a normal scanning operation of the fingerprint sensor is initiated, thus ensuring that the complete fingerprint images produced are of satisfactory quality.

Abstract: A filter circuit comprises a balanced port, an unbalanced port and a substrate. A series circuit of a filter stage and a balun is disposed between the balanced port and the unbalanced port. The balun and the filter stage are formed on the substrate.

Abstract: A BAW resonator includes a resonator region having a piezo-electric layer between two excitation electrodes, wherein an acoustic standing wave forms when operating the BAW resonator at a resonant frequency. Furthermore, the BAW resonator includes a leaky wave reflection structure formed to reflect leaky waves generated when operating the BAW resonator, wherein the leaky waves propagate in a direction differing from a propagation direction of the acoustic standing wave.

Abstract: A BAW resonator includes a resonator region having a piezo-electric layer between two excitation electrodes, wherein an acoustic standing wave forms when operating the BAW resonator at a resonant frequency. Furthermore, the BAW resonator includes a leaky wave reflection structure formed to reflect leaky waves generated when operating the BAW resonator, wherein the leaky waves propagate in a direction differing from a propagation direction of the acoustic standing wave.

Abstract: A BAW resonator includes a first piezoelectric layer made of a material oriented toward a first direction, and a second piezoelectric layer made of a material oriented toward a second direction which is opposed to the first direction. The first piezoelectric layer and the second piezoelectric layer are acoustically coupled with each other.

Abstract: A filter circuit comprises a balanced port, an unbalanced port and a substrate. A series circuit of a filter stage and a balun is disposed between the balanced port and the unbalanced port. The balun and the filter stage are formed on the substrate.

Abstract: A bulk acoustic wave (BAW) filter (40) is fabricated from thin film bulk acoustic wave resonators and a method eliminates unwanted side passbands. This BAW filter comprises a substrate (14) a resonator section (11) and an acoustic mirror section (12). Further it comprises a detuning component (31) positioned in the resonator section (11) to provide precise passband characteristics and an additional detuning component (41) in the acoustic mirror section (12) to suppress unwanted side-passband characteristics.

Abstract: A BAW resonator includes a piezoelectric layer, a first electrode, a second electrode, a substrate, and an acoustic reflector disposed between the substrate and the second electrode. The acoustic reflector has a plurality of layers. A performance of the acoustic reflector is determined by its reflectivity for a longitudinal wave existing in the BAW resonator at the resonance frequency of the BAW resonator and by its reflectivity for a shear wave existing in the BAW resonator at the resonance frequency of the BAW resonator. The layers of the acoustic reflector and layers disposed between the acoustic reflector and the piezoelectric layer are selected, with reference to their number, material, and thickness, such that the transmissivity for the longitudinal wave and the transmissivity for the shear wave in the area of the resonance frequency is smaller than ?10 dB.

Abstract: The invention relates to bulk acoustic wave filters including at least two bulk acoustic wave resonators. Each of these resonators includes at least one first electrode, a piezoelectric layer, and a second electrode. At least two of the bulk acoustic wave resonators have effective resonator surfaces which differ in their surface form and/or surface content. The inventive design of the bulk acoustic wave resonators enables optimal suppression of interference modes without influencing the impedance level of the filter.

Abstract: A semiconductor component is provided having a layer sequence for conversion of acoustic to thermal signals and electrical voltage changes to one another, as well as a process for its production. The layer sequence has a lower electrode, an upper electrode and a layer which is arranged between them and is piezoelectrical or pyroelectrical. An auxiliary layer is arranged between the lower electrode and the layer and is used for homogeneously oriented growth of the layer during the production process. The auxiliary layer preferably consists essentially of amorphous silicon, amorphous silicon oxide or amorphous silicon nitride.

Abstract: In a method for manufacturing a piezoelectric oscillating circuit in thin film technology, wherein the oscillating circuit includes a predetermined natural frequency and a plurality of layers, first of all at least a first layer of the piezoelectric oscillating circuit is generated. Subsequently, by processing the first layer a frequency correction is performed. Subsequently, at least a second layer of the piezoelectric oscillating circuit is generated and processed for performing a second frequency correction.

Abstract: A resonator device includes a piezoelectric resonator having a detuning layer sequence arranged on the piezoelectric resonator. The detuning layer sequence includes at least a first layer having a high acoustic impedance and a second layer having a low acoustic impedance.

Abstract: A BAW resonator includes a first piezoelectric layer made of a material oriented toward a first direction, and a second piezoelectric layer made of a material oriented toward a second direction which is opposed to the first direction. The first piezoelectric layer and the second piezoelectric layer are acoustically coupled with each other.

Abstract: A resonator apparatus has a piezoelectric resonator as well as an acoustic reflector which has a layer having a high acoustic impedance and a layer having a low acoustic impedance. The thickness of one layer is set different from a quarter of the wavelength in this layer at the operating frequency due to technological limitations in the manufacturing of this layer, and the thickness of the other layer is set dependent from the one layer, such that a predetermined minimum quality of the acoustic reflector is attained.

Abstract: A method for producing a layer with a locally adapted or predefined layer thickness profile that can be used for to selectively set the natural frequencies of piezoelectric resonant circuits and/or the impedance of other circuit elements. A layer is applied to a substrate, then measured to determine a difference between the initial layer thickness and the predefined layer thickness profile. An ion beam is then used to etch (mill) the layer until it achieves the predefined layer thickness profile.

Abstract: The invention describes a method for producing a piezoelectric component comprising at least two stacked crystal filters. By means of the deposition of the layer stack above the bottom electrode and the subsequent patterning of the upper electrically conductive layer and, if appropriate, second piezoelectric layer, it is possible, in a simple manner, with a minimum of process steps, to produce a piezoelectric component comprising two stacked crystal filters which are directly connected to one another via their bottom and central electrodes. The piezoelectric component according to the invention furthermore has the advantage that applications in which a high stop band attenuation is important can be realized with a relatively small number of filter stages. In this case, through the use of at least two stacked crystal filters, it is possible to achieve an excellent out-of-band rejection also for “single-ended signals”.

Abstract: A resonator apparatus has a piezoelectric resonator as well as an acoustic reflector which has a layer having a high acoustic impedance and a layer having a low acoustic impedance. The thickness of one layer is set different from a quarter of the wavelength in this layer at the operating frequency due to technological limitations in the manufacturing of this layer, and the thickness of the other layer is set dependent from the one layer, such that a predetermined minimum quality of the acoustic reflector is attained.

Abstract: A BAW resonator includes a piezoelectric layer with a first surface and a second surface opposing the first surface, a first electrode disposed on the first surface of the piezoelectric layer, a second electrode disposed on the second surface of the piezoelectric layer, a substrate, and an acoustic reflector disposed between the substrate and the second electrode, the acoustic reflector comprising a plurality of layers from a material with high acoustic impedance and from a material with low acoustic impedance, wherein areas with layers with high acoustic impedance and areas with layers with low acoustic impedance are alternately adjacently disposed. A performance of the acoustic reflector is determined by its reflectivity for a longitudinal wave existing in the BAW resonator at the resonance frequency of the BAW resonator and by its reflectivity for a shear wave existing in the BAW resonator at the resonance frequency of the BAW resonator.

Abstract: A resonator device includes a piezoelectric resonator having a detuning layer sequence arranged on the piezoelectric resonator. The detuning layer sequence includes at least a first layer having a high acoustic impedance and a second layer having a low acoustic impedance.