Capacitive device and resonance circuit
To provide a capacitive device capable of accurately securing a capacitance value, a variable capacitive device capable of sufficiently securing a capacity variability rate, and a resonance circuit that uses the capacitive devices. A capacitive device includes a capacitive device body constituted of a dielectric layer and at least a pair of capacitive device electrodes that sandwich the dielectric layer and cause a desired electric field in the dielectric layer; and stress adjustment portions to adjust a stress caused in the dielectric layer of the capacitive device body.
1. A resonance circuit, comprising:
a resonance capacitor comprising a capacitive device that comprises
a capacitive device body comprising a dielectric layer and at least a pair of capacitive device electrodes that sandwich the dielectric layer and cause a desired electric field in the dielectric layer,
a stress adjustment portion that adjusts a stress caused in the dielectric layer of the capacitive device body, wherein the stress adjustment portion comprises a stress adjustment dielectric layer and a plurality of stress adjustment electrodes laminated in the stress adjustment dielectric layer;
at least a first pair of external electrodes connected to the at least a pair of capacitive device electrodes; and
at least a second pair of external electrodes connected to the plurality of stress adjustment electrodes; and
a resonance coil connected to the resonance capacitor.
2. A capacitive device, comprising:
a capacitive device body comprising a dielectric layer and at least a pair of capacitive device electrodes that sandwich the dielectric layer and cause a desired electric field in the dielectric layer;
a stress adjustment portion to adjust a stress caused in the dielectric layer of the capacitive device body, wherein the stress adjustment portion comprises a stress adjustment dielectric layer and a plurality of stress adjustment electrodes laminated in the stress adjustment dielectric layer;
at least a first pair of external electrodes connected to the at least a pair of capacitive device electrodes; and
at least a second pair of external electrodes connected to the plurality of stress adjustment electrodes.
3. The capacitive device according to claim 2 ,
wherein the stress adjustment portion is laminated in a thickness direction of the dielectric layer of the capacitive device body.
4. The capacitive device according to claim 3 ,
wherein the stress adjustment portion sandwiches the capacitive device body.
5. The capacitive device according to claim 4 ,
wherein the at least a pair of capacitive device electrodes and the plurality of stress adjustment electrodes are in parallel, and
wherein a stress adjustment voltage is applied to the plurality of stress adjustment electrodes.
6. The capacitive device according to claim 5 , wherein the stress adjustment voltage comprises antipolar voltages;
the plurality of stress adjustment electrodes to which the antipolar voltages are applied are arranged alternately in the stress adjustment portion.
7. The capacitive device according to claim 6 ,
wherein the dielectric layer is formed of a ferroelectric material having a capacity that changes based on a control voltage, and the control voltage is applied between the pair of capacitive device electrodes.
8. The capacitive device according to claim 7 ,
wherein the stress adjustment voltage is larger than the control voltage.
9. The capacitive device according to claim 2 ,
wherein the plurality of stress adjustment electrodes are electrically connected to the at least a pair of capacitive device electrodes.
10. The capacitive device according to claim 2 ,
wherein the plurality of stress adjustment electrodes float electrically.
11. The capacitive device according claim 2 ,
wherein a plurality of the at least a pair of capacitive device electrodes are laminated via the dielectric layer in the capacitive device body.