A varainductor includes a signal line over a substrate. The varainductor further includes a first ground plane over the substrate. The varainductor further includes a first floating plane over the substrate, wherein the first floating plane is between the first ground plane and the signal line, and the first floating plane is a same distance from the substrate as the first ground plane. The varainductor further includes a first transistor configured to selectively electrically connect the first ground plane to the first floating plane. The varainductor further includes a second transistor configured to selectively electrically connect the first ground plane to the first floating plane, wherein a gate of the first transistor is connected to a gate of the second transistor.

A method includes sending, by a reader, a radio frequency (RF) signal to a wireless sensor that includes an antenna having a tail section and a head section. The tail section is for placement in an RF limited area for sensing moisture in a first location of a vehicle under test and wherein the head section is for placement in a non-RF limited area. The method further includes receiving, by the reader, an RF response to the RF signal from the wireless sensor. The first RF response includes an indication of adjustment of one or more RF characteristics of the wireless sensor, which corresponds to a variance of the one or more RF characteristics from a desired value, which, in turn, corresponds to a level of moisture at the first location. The method further includes outputting, by the reader, a message regarding the level of moisture at the first location.

A method includes sending, by a reader, a radio frequency (RF) signal to a wireless sensor that includes an antenna having a tail section and a head section. The tail section is for placement in an RF limited area for sensing moisture in a first location of a vehicle under test and wherein the head section is for placement in a non-RF limited area. The method further includes receiving, by the reader, an RF response to the RF signal from the wireless sensor. The first RF response includes an indication of adjustment of one or more RF characteristics of the wireless sensor, which corresponds to a variance of the one or more RF characteristics from a desired value, which, in turn, corresponds to a level of moisture at the first location. The method further includes outputting, by the reader, a message regarding the level of moisture at the first location.

Techniques are described for tuning a resonant circuit using differential switchable capacitors. For example, embodiments can operate in context of a power amplifier with a tunable resonant output network. To tune the network, multiple differential switchable capacitors are provided in parallel. Each differential switchable capacitor can include a pair of capacitors, each coupled between a respective internal node and a respective differential terminal; and the internal nodes are selectively coupled or decoupled using a respective electronic switch (e.g., transistor). Switching on one of the differential switchable capacitors forms a capacitive channel having an associated capacitance. Each differential switchable capacitor can also include a switch network to selectively pull the internal nodes to a high or low voltage reference according to the selected operating mode.

Techniques are described for tuning a resonant circuit using differential switchable capacitors. For example, embodiments can operate in context of a power amplifier with a tunable resonant output network. To tune the network, multiple differential switchable capacitors are provided in parallel. Each differential switchable capacitor can include a pair of capacitors, each coupled between a respective internal node and a respective differential terminal; and the internal nodes are selectively coupled or decoupled using a respective electronic switch (e.g., transistor). Switching on one of the differential switchable capacitors forms a capacitive channel having an associated capacitance. Each differential switchable capacitor can also include a switch network to selectively pull the internal nodes to a high or low voltage reference according to the selected operating mode.

An electronic component such as a voltage controllable reconfigurable capacitor or transistor is formed by printing one or more layers of ink on a non-conductive substrate. Ferroelectric ink or semi-conductive ink is printed and conductive resistive or dielectric ink is printed on a s same or different layers. Reconfigurability is achieved by printing resistive biasing circuitry wherein when a changing voltage is applied to the biasing circuitry, an electronic property of the electronic component changes in response to the changing voltage.

An electronic component such as a voltage controllable reconfigurable capacitor or transistor is formed by printing one or more layers of ink on a non-conductive substrate. Ferroelectric ink or semi-conductive ink is printed and conductive resistive or dielectric ink is printed on a s same or different layers. Reconfigurability is achieved by printing resistive biasing circuitry wherein when a changing voltage is applied to the biasing circuitry, an electronic property of the electronic component changes in response to the changing voltage.

A radio frequency identification (RFID) tag includes an antenna, a power circuit, a tuning circuit, a receiver, and a backscatter transmitter. The power circuit is operably coupled to convert a radio frequency (RF) signal received via the antenna from an RFID reader into one or more power supply voltages. The tuning circuit is operably coupled to the antenna and to adjust an RF characteristic of the antenna and/or the tuning circuit based on a difference between a resonant frequency of the RFID tag and a carrier frequency of the RF signal. The receiver is operably coupled to receive a command signal from the RFID reader. The backscatter transmitter is operably coupled to transmit a response signal to the RFID reader via the antenna.

A radio frequency identification (RFID) tag includes an antenna, a power circuit, a tuning circuit, a receiver, and a backscatter transmitter. The power circuit is operably coupled to convert a radio frequency (RF) signal received via the antenna from an RFID reader into one or more power supply voltages. The tuning circuit is operably coupled to the antenna and to adjust an RF characteristic of the antenna and/or the tuning circuit based on a difference between a resonant frequency of the RFID tag and a carrier frequency of the RF signal. The receiver is operably coupled to receive a command signal from the RFID reader. The backscatter transmitter is operably coupled to transmit a response signal to the RFID reader via the antenna.

Devices and methods for improving voltage handling and/or bi-directionality of stacks of elements when connected between terminals are described. Such devices and method include use of symmetrical compensation capacitances, symmetrical series capacitors, or symmetrical sizing of the elements of the stack.