A semiconductor device comprising a semiconductor substrate and a composite capacitor structure on the semiconductor substrate, wherein the composite capacitor structure comprises a capacitor stack comprising a lower and an upper capacitor, respectively comprising first and second dielectric materials, wherein the first and second dielectric materials are different materials and/or have different thicknesses from each other. This can minimize the voltage dependence of the capacitance of the composite capacitor structure. It is also possible to provide a composite capacitor structure on the semiconductor substrate, wherein the composite capacitor structure comprises at least a first and a second capacitor stack, each comprising a lower and an upper capacitor. The capacitors can be MIM capacitors.

The invention relates to a variable-capacitance electrical capacitor comprising a first electrode and a second electrode facing the first electrode and a zone of a dielectric material arranged between said first and second electrodes characterized in that the second electrode is formed at least on one hand of a primary electrode made of an electrically conductive material and, at least on the other, of an additional electrode comprising a state-change material, the primary electrode and the additional electrode facing the first electrode, said state-change material being arranged at least partially in contact with the primary electrode and configured to alternatively adopt a high-resistivity state wherein the additional electrode is electrically insulated from the primary electrode and a low-resistivity state wherein the additional electrode is in electrical conduction with the primary electrode so as to vary the electrically active surface area of the second electrode.

The invention relates to a variable-capacitance electrical capacitor comprising a first electrode and a second electrode facing the first electrode and a zone of a dielectric material arranged between said first and second electrodes characterized in that the second electrode is formed at least on one hand of a primary electrode made of an electrically conductive material and, at least on the other, of an additional electrode comprising a state-change material, the primary electrode and the additional electrode facing the first electrode, said state-change material being arranged at least partially in contact with the primary electrode and configured to alternatively adopt a high-resistivity state wherein the additional electrode is electrically insulated from the primary electrode and a low-resistivity state wherein the additional electrode is in electrical conduction with the primary electrode so as to vary the electrically active surface area of the second electrode.

A variable filter circuit includes a serial arm connected between ports (P1-P2), a parallel arm having a resonator connected in series between ports (P1-P3), and another parallel arm having another resonator connected in series between ports (P2-P3). The serial arm includes a capacitor connected between the ports (P1-P2), and the parallel arms include variable capacitances connected in series to the resonators.

A variable filter circuit includes a serial arm connected between ports (P1-P2), a parallel arm having a resonator connected in series between ports (P1-P3), and another parallel arm having another resonator connected in series between ports (P2-P3). The serial arm includes a capacitor connected between the ports (P1-P2), and the parallel arms include variable capacitances connected in series to the resonators.

A magnetic supercapacitor has a dielectric layer positioned between magnetic layers. The magnetic layers may comprise hard, soft magnetic material or magnetic exchange coupled magnet (i.e. soft and hard magnet composite). A magnetic flux generated by the magnetic layers increases the permittivity of the dielectric layer, thereby increasing the capacitance and, hence, stored energy of the supercapacitor. When the magnetic layers comprise soft magnetic material, the capacitance of the supercapacitor can be varied. In this regard, current passing through a conductive segment within close proximity to the magnetic layers may be controlled in order to tune the capacitance as may be desired.

A magnetic supercapacitor has a dielectric layer positioned between magnetic layers. The magnetic layers may comprise hard, soft magnetic material or magnetic exchange coupled magnet (i.e. soft and hard magnet composite). A magnetic flux generated by the magnetic layers increases the permittivity of the dielectric layer, thereby increasing the capacitance and, hence, stored energy of the supercapacitor. When the magnetic layers comprise soft magnetic material, the capacitance of the supercapacitor can be varied. In this regard, current passing through a conductive segment within close proximity to the magnetic layers may be controlled in order to tune the capacitance as may be desired.

A ferroelectric capacitor having a doped graphene bottom electrode and uses thereof are described. The doped graphene bottom electrode layer is deposited on a substrate with a ferroelectric layer deposited between the doped graphene layer and a top electrode.

A first capacitor has a capacitance adjustable to a set point value by application of a bias voltage. A second capacitor also has a capacitance adjustable to a set point value by application of a bias voltage. The first and second capacitors are arranged to receive the same bias voltage generated by a control circuit. The control circuit receiving the set point value as an input and generates that bias voltage in response to a quantity representative of a capacitance of the second capacitor.

A variable capacitance capacitor element according to an embodiment of the present invention comprises: a supporting substrate; a first electrode layer provided on the supporting substrate; a second electrode layer provided opposite to the first electrode layer; and a dielectric layer positioned between the first electrode layer and the second electrode layer. In accordance with an aspect, a main component of the dielectric layer is represented by a composition formula Ba.sub.1−xSr.sub.xTiO.sub.3 (0.5≦x≦0.8), and the first thin film dielectric layer has a thickness of 200 nm or smaller.