Driving methods to minimize the effect of leakage current in tunable elements

An antenna comprising:

• a plurality of radio-frequency (RF) radiating antenna elements, wherein each antenna element of the plurality of RF radiating antenna elements comprises
• a tunable element subject to voltage degradation over time between write cycles in which drive voltages are written to tunable elements of the plurality of RF radiating antenna elements, wherein the tunable element comprises a varactor or a MEMS capacitor,
• circuitry connected to the tuning element to set a voltage on the tunable element, the circuitry comprising
• a voltage storage structure,
• a first transistor having a first gate connected to the voltage storage structure, a first source connected to the tunable element, and a first drain for coupling to a constant voltage source to provide a drain-to-source voltage to the tunable element and create a leakage current path through the tunable element, the first transistor operable to decouple the voltage storage structure from the leakage current path to prevent the voltage degradation,
• a resistor coupled to the first source and ground and coupled in parallel with the tunable element, and
• a data voltage input terminal operable to apply a voltage to the voltage storage structure and to the first gate to determine current through the first transistor as a current source for the leakage current through the tunable element.

An antenna comprising:

• a plurality of radio-frequency (RF) radiating antenna elements, wherein each antenna element of the plurality of RF radiating antenna elements comprises
• a tunable element subject to voltage degradation over time between write cycles in which a pattern of drive voltages is written to tunable elements of the plurality of RF radiating antenna elements, wherein the tunable element comprises a varactor or a MEMS capacitor,
• circuitry connected to the tuning element to set a voltage on the tunable element, the circuitry comprising
• a voltage storage structure,
• a first transistor having a first gate connected to the voltage storage structure, a first source connected to the tunable element, and a first drain for coupling to a non- constant voltage source to provide a drain-to-source voltage to the tunable element and create a leakage current path through the tunable element, the first transistor operable to decouple the voltage storage structure from the leakage current path to prevent the voltage degradation,
• a capacitor load coupled to the first source and ground and coupled in parallel with the tunable element, wherein the capacitor load is charged by the non-constant voltage source, holds charge in between the write cycles in which the pattern of drive voltages is written, and discharges during each of the write cycles, and
• a data voltage input terminal operable to apply a voltage to the voltage storage structure and to the first gate to determine current through the first transistor as a current source for the tunable element.