Patent ID: 7274277

Claim:
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.