Ferroelectric devices and method relating thereto
View Patent ↗The present invention relates to an electrically controllable/tunable microwave device comprising a ferroelectric substrate with a variable dielectric permitivity and conducting electrodes, arranged on said substrate, and the capacitance of which depends on applied voltage C/V), the microwave device comprises at least two sections or parts of the substrate/electrodes for each of which different electrical field strengths are generated upon voltage application. Said generated electrical field strengths are controlled by means of the design of the device and/or the voltage application such that the slope (dC(dV) of the voltage dependence of the capacitance (C(V) of the microwave device can be controlled.
1. An electrically controllable/tunable microwave device having a capacitance which depends on applied voltage, the device comprising:
a thin film ferroelectric substrate with a variable dielectric permittivity;
planar conducting electrodes arranged on said substrate;
wherein the microwave device comprises at least two sections or parts of the substrate/electrodes for each of which different electrical field strengths are generated upon voltage application;
wherein the planar electrodes are disposed on the substrate such that a gap is formed between protruding portions of said electrodes, and wherein the gap between the protruding portions of the electrodes has a varying width configured in accordance with a desired dependence of the capacitance on the applied voltage; and
wherein the device is so shaped and/or (a) voltage(s) is/are so applied that the slope of the dependence of the capacitance on voltage will be linear dC/dV being constant.
2. A microwave device according to claim 1 , wherein said generated electrical field strengths are controlled by means of design of the device and/or the voltage application such that the slope of the voltage dependence of the capacitance of the microwave device can be controlled.
3. The apparatus of claim 1 , wherein generation of different electric fields in different parts/sections or of a continuously varying electric field exclusively is given by the design of the ferroelectric substrate and/or the conducting electrodes.
4. A microwave device according to claim 1 , wherein the protruding portions of the electrodes are not parallel.
5. A microwave device according to claim 1 , wherein the gap between the protruding portions essentially continuously varies.
6. An electrically controllable/tunable microwave device having a capacitance which depends on applied voltage, the device comprising:
a thin film ferroelectric substrate with a variable dielectric permittivity;
planar conducting electrodes arranged on said substrate;
wherein the microwave device comprises at least two sections or parts of the substrate/electrodes for each of which different electrical field strengths are generated upon voltage application;
wherein the planar electrodes are disposed on the substrate such that a gap is formed between protruding portions of said electrodes, and wherein the gap between the protruding portions of the electrodes has a varying width configured in accordance with a desired dependence of the capacitance on the applied voltage; and
wherein the gap has a varying width configured in accordance with a linear dependence of the capacitance on the applied voltage.
7. A microwave device according to claim 6 , wherein the gap has a varying width shaped whereby a slope of the dependence of the capacitance on applied voltage can be controlled.
8. A microwave device according to claim 6 , wherein the substrate comprises SrTiO 3 .
9. An electrically controllable/tunable microwave device having a capacitance which depends on applied voltage, the device comprising:
a thin film ferroelectric substrate with a variable dielectric permittivity;
planar conducting electrodes arranged on said substrate;
wherein the microwave device comprises at least two sections or parts of the substrate/electrodes for each of which different electrical field strengths are generated upon voltage application;
wherein the planar electrodes are disposed on the substrate such that a gap is formed between protruding portions of said electrodes, and wherein the gap between the protruding portions of the electrodes has a varying width configured in accordance with a desired dependence of the capacitance on the applied voltage; and
wherein the protruding portions of the electrodes have an arc shape.