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.

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.

An apparatus for converting power includes at least one impedance matching network which receives an electrical signal. The apparatus includes at least one AC to DC converter in communication with the impedance matching network. Also disclosed is a method for powering a load and an apparatus for converting power and additional embodiments of an apparatus for converting power.

An apparatus for converting power includes at least one impedance matching network which receives an electrical signal. The apparatus includes at least one AC to DC converter in communication with the impedance matching network. Also disclosed is a method for powering a load and an apparatus for converting power and additional embodiments of an apparatus for converting power.

In an RFIC provided in a semiconductor device according to an embodiment, a low-noise amplifier (41) for reception and a power amplifier (11) for transmission are connected to a common antenna connection terminal (5). Between the antenna connection terminal (5) and an LNA (41), a circuit (31) is connected to be used for impedance matching, and a semiconductor switch (SW1) is connected in parallel with the circuit (31).

In an RFIC provided in a semiconductor device according to an embodiment, a low-noise amplifier (41) for reception and a power amplifier (11) for transmission are connected to a common antenna connection terminal (5). Between the antenna connection terminal (5) and an LNA (41), a circuit (31) is connected to be used for impedance matching, and a semiconductor switch (SW1) is connected in parallel with the circuit (31).

Methods, systems, and devices for controlling a variable capacitor. One aspect features a variable capacitance device that includes a capacitor, a first transistor, a second transistor, and control circuitry. The control circuitry is configured to adjust an effective capacitance of the capacitor by performing operations including detecting a zero-crossing of an input current at a first time. Switching off the first transistor. Estimating a first delay period for switching the first transistor on when a voltage across the capacitor is zero. Switching on the first transistor after the first delay period from the first time. Detecting a zero-crossing of the input current at a second time. Switching off the second transistor. Estimating a second delay period for switching the second transistor on when a voltage across the capacitor is zero. Switching on the second transistor after the second delay period from the second time.

Methods, systems, and devices for controlling a variable capacitor. One aspect features a variable capacitance device that includes a capacitor, a first transistor, a second transistor, and control circuitry. The control circuitry is configured to adjust an effective capacitance of the capacitor by performing operations including detecting a zero-crossing of an input current at a first time. Switching off the first transistor. Estimating a first delay period for switching the first transistor on when a voltage across the capacitor is zero. Switching on the first transistor after the first delay period from the first time. Detecting a zero-crossing of the input current at a second time. Switching off the second transistor. Estimating a second delay period for switching the second transistor on when a voltage across the capacitor is zero. Switching on the second transistor after the second delay period from the second time.

A wireless power transmission device for wirelessly transmitting power to at least one wireless power reception device through a magnetic field, the wireless power transmission device including: a power transmission unit for generating a magnetic field, an impedance matching unit, and a control unit for controlling the impedance matching unit, the impedance matching unit including: a plurality of first circuits which include a capacitor or an inductor and are connected in series to the power transmission unit; a plurality of second circuits which include a capacitor or an inductor and are connected in parallel to the power transmission unit; a matching inductor which is connected in series to the second circuits; and a plurality of switches which are arranged in the first circuits and second circuits and open and close same.

A wireless power transmission device for wirelessly transmitting power to at least one wireless power reception device through a magnetic field, the wireless power transmission device including: a power transmission unit for generating a magnetic field, an impedance matching unit, and a control unit for controlling the impedance matching unit, the impedance matching unit including: a plurality of first circuits which include a capacitor or an inductor and are connected in series to the power transmission unit; a plurality of second circuits which include a capacitor or an inductor and are connected in parallel to the power transmission unit; a matching inductor which is connected in series to the second circuits; and a plurality of switches which are arranged in the first circuits and second circuits and open and close same.