A plasma generator and a method for setting an ion ratio. In an embodiment a plasma generator includes a piezoelectric transformer suitable for ionizing a process gas, an ion separation electrode and a drive circuit suitable for applying a potential to the ion separation electrode.

A composite substrate production method of the invention includes (a) a step of mirror polishing a substrate stack having a diameter of 4 inch or more, the substrate stack including a piezoelectric substrate and a support substrate bonded to each other, the mirror polishing being performed on the piezoelectric substrate side until the thickness of the piezoelectric substrate reaches 3 m or less; (b) a step of creating data of the distribution of the thickness of the mirror-polished piezoelectric substrate; and (c) a step of performing machining with an ion beam machine based on the data of the thickness distribution so as to produce a composite substrate have some special technical features.

A power converter including at least one piezoelectric element in a branch of a bridge of switches, the switches being controlled to alternate phases at substantially constant voltage and at substantially constant charge between the terminals of the piezoelectric element.

A power converter including: a first branch and a second branch of at least two series-connected switches each, coupled in parallel between a first terminal and a second terminal and having the junction points of their switches coupled to two terminals of application of a first voltage; a third branch and a fourth branch of at least two series-connected switches each, coupled in parallel between a third terminal and a fourth terminal, and having the junction points of their switches coupled to two terminals for supplying a second voltage; and at least one piezoelectric element coupling the first terminal to the third terminal.

A device for generating an atmospheric-pressure plasma is disclosed. In an embodiment the device includes a piezoelectric transformer comprising an input region and an output region, wherein the input region is designed to convert an applied alternating voltage into a mechanical oscillation, wherein the output region is designed to convert a mechanical oscillation into a voltage, and wherein the output region adjoins the input region in a longitudinal direction, a contact element fastened to the piezoelectric transformer, the contact element being designed to apply the alternating voltage to the input region and a holder, wherein the contact element is connected to the holder by a form-fit connection, in such a manner that a movement of the piezoelectric transformer in the longitudinal direction, relative to the holder, is prevented.

A device for producing a non-thermal atmospheric-pressure plasma are a method for frequency control of a piezoelectric transformer are disclosed. In an embodiment a device includes a piezoelectric transformer, an activating circuit configured to apply an AC voltage at an activating frequency to the piezoelectric transformer as an input voltage and a field probe configured to measure a field strength of an electric field produced by the piezoelectric transformer, wherein the activating circuit is configured to adapt the activating frequency based on the measurement results of the field probe such that a field strength is maximized.

A device for producing a non-thermal atmospheric pressure plasma and an active space including such a device are disclosed. In an embodiment a device includes a first housing, in which a piezoelectric transformer is arranged and a second housing, in which a control circuit is arranged, the control circuit configured to apply an input voltage to the piezoelectric transformer, wherein the first housing comprises a coating configured to eradicate irritant gases.

The present disclosure relates to a Wafer-level-packaged Bulk Acoustic Wave (BAW) device, which includes a bottom electrode, a top electrode, a top electrode lead, a piezoelectric layer sandwiched between the bottom and the top electrodes, an enclosure, and an anti-reflective layer (ARL). Herein, an active region for a resonator is formed where the bottom electrode and the top electrode overlap. The top electrode lead is over the piezoelectric layer and extending from the top electrode. The enclosure includes a cap and an outer wall that extends from the cap toward the piezoelectric layer to form a cavity. The top electrode resides in the cavity and a first portion of the outer wall resides over the top electrode lead. The ARL, with a reflectance less than 40% R, is between the first portion of the outer wall and the top electrode lead.

A plasma generator capable of adjusting the amount of plasma generation in a simple configuration includes a control circuit controlling a frequency of an AC power supplied to a piezoelectric transformer and a control signal generation circuit providing a control signal to the control circuit. The plasma generator is configured so that the control signal output from the control signal generation circuit is appropriately adjusted. The control circuit controls the frequency of the AC power so as to bring a target value, which is set based on the control signal provided from the control signal generation circuit.

There is provided a piezoelectric transformer including a first output terminal, a first piezoelectric element connected to the first output terminal, a second output terminal, a second piezoelectric element connected to the second output terminal, an input terminal, and a third piezoelectric element connected to the input terminal, wherein each of the first and second output terminals is formed to be individually connectable to a corresponding external load and outputs a voltage at a different frequency.