Abstract: The resonator comprises a first electrode (E1), a second electrode (E2) and a piezoelectric layer (P) arranged between the above. A first acoustic compression layer (V1) is arranged between the piezoelectric layer (E1) and the first electrode (E1) with a higher acoustic impedance than the first electrode (E1).

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: The layer sequence has a lower electrode (U), an upper electrode (O) and a layer (S) which is arranged between them and is piezoelectrical or pyroelectrical. An auxiliary layer (H) is arranged between the lower electrode (U) and the layer (S) and is used for homogeneously oriented growth of the layer (S) during the production process. The auxiliary layer (H) is preferably composed essentially of amorphous silicon, amorphous silicon oxide or amorphous silicon nitride.

Abstract: A characteristic curve of the impedance of a skin surface is measured as a function of the frequency of an electric AC voltage by applying the voltage to at least one electric conductor which is galvanically or capacitively coupled to the skin surface. The characteristic curve is compared with a reference characteristic curve, which has been generated previously. If the characteristic curve substantially corresponds to the reference characteristic curve, the skin surface is recognized as belonging to living tissue.

Abstract: An acoustic mirror is described which is formed of at least one first insulating layer, a first metal layer disposed thereon, a second insulating layer disposed thereon and a second metal layer disposed thereon. An auxiliary layer is produced on the first insulating layer whereby a recess extending as far as the first insulating layer is created therein. The first metal layer is substantially deposited and removed by chemical/mechanical polishing until the parts of the first metal layer disposed outside the recess are no longer present. The second metal layer is also produced in a recess with the aid of chemical/mechanical polishing. More than two insulating layers and two metal layers can be provided. The first metal layer and the second metal layer can be produced in the same recess.

Abstract: A thin film piezoresonator, which can be tuned over a wide range of RF frequencies, includes a piezo layer between a first electrode layer and a second electrode layer. An electroactive layer of an electrostrictive material, which experiences a mechanical deformation when an electrical voltage is applied, is disposed between a third electrode layer and the second electrode layer.

Abstract: The circuit arrangement or the operating method ensure that the fingerprint sensor is started automatically when a sufficiently high-contrast image can be produced. To this end, test runs are carried out in which only pan of the pixels, for instance along a column or line of a matrix-like array in a square raster, are taken into account. It is determined whether the difference between the maximum and minimum values of the sensor signals exceeds a predetermined value. In said case, the normal scanning procedure of the fingerprint sensor is started.

Abstract: An acoustic mirror is described which is formed of at least one first insulating layer, a first metal layer disposed thereon, a second insulating layer disposed thereon and a second metal layer disposed thereon. An auxiliary layer is produced on the first insulating layer whereby a recess extending as far as the first insulating layer is created therein. The first metal layer is substantially deposited and removed by chemical/mechanical polishing until the parts of the first metal layer disposed outside the recess are no longer present. The second metal layer is also produced in a recess with the aid of chemical/mechanical polishing. More than two insulating layers and two metal layers can be provided. The first metal layer and the second metal layer can be produced in the same recess.

Abstract: A grid-shaped array of conductor areas is used for capacitive image acquisition. Shielding conductors are disposed in each case between the conductors that are provided for measurement. During a plurality of charging and discharging cycles, the potential is always carried along on the conductors belonging to a respective pixel in order to prevent displacement currents between the shielding capacitors. By way of example, a compensation line with a feedback operational amplifier can be used for identically altering the electrical potentials on the conductors.

Abstract: A grid-shaped array of conductor areas is used for capacitive image acquisition. Shielding conductors are disposed in each case between the conductors that are provided for measurement. During a plurality of charging and discharging cycles, the potential is always carried along on the conductors belonging to a respective pixel in order to prevent displacement currents between the shielding capacitors. By way of example, a compensation line with a feedback operational amplifier can be used for identically altering the electrical potentials on the conductors.

Abstract: A thin film piezoresonator, which can be tuned over a wide range of RF frequencies, includes a piezo layer between a first electrode layer and a second electrode layer. An electroactive layer of an electrostrictive material, which experiences a mechanical deformation when an electrical voltage is applied, is disposed between a third electrode layer and the second electrode layer.

Abstract: A characteristic curve of the impedance of a skin surface is measured as a function of the frequency of an electric AC voltage by applying the voltage to at least one electric conductor which is galvanically or capacitively coupled to the skin surface. The characteristic curve is compared with a reference characteristic curve, which has been generated previously. If the characteristic curve substantially corresponds to the reference characteristic curve, the skin surface is recognized as belonging to living tissue.