Systems and methods are provided for dynamically biasing power amplifiers. In particular, dynamic biasing of a power amplifier may be controlled, with the controlling comprising receiving an input signal that is to be amplified; processing the input signal; generating based on said processing of the input signal input signal, a plurality of control signals comprising at least one biasing control signal; and applying the plurality of control signals to one or more control elements that are used in driving and/or control of the power amplifier. The one or more control elements may comprise at least one biasing component that adjusts biasing applied to power amplifier.

A quadrature modulator and the transmission unit output a modulated wave obtained by performing quadrature modulation on a carrier wave using a first I signal and a first Q signal and wirelessly transmit the modulated wave. A reception unit and the quadrature detector detect a received signal corresponding to a wireless signal transmitted from the wireless tag using the carrier wave and to output a second I signal and a second Q signal. A filter and the amplification unit amplify a frequency component higher than a cutoff frequency in the second I signal and the second Q signal. A detector and the decoding unit decode data based on a detection signal obtained by detecting the amplified second I signal and the amplified second Q signal. A generation unit generates the first I signal and the first Q signal such that the modulated wave is a signal obtained by shifting a frequency of the carrier wave by a frequency shift amount more than the cutoff frequency and to input the first I signal and the first Q signal to the quadrature modulator.

A filter device configured to directly connect to a differential power amplifier of a transmit chain circuit. The filter device may include a transformer and a filter configured as a half lattice equivalent topology and having a single-ended output. The filter may be a lattice filter configured as a full lattice topology or a lattice equivalent filter configured as a half lattice equivalent topology. The filter includes a first branch having a first impedance network of one or more first impedance elements and a second branch having a second impedance network of one or more second impedance elements. The single-ended output of the filter device may connect to an antenna switch that is in turn connected to an antenna.

A combining balun includes: a first input side conductive member wound around a first axis on a first surface, which intersects with the first axis, and has a first portion between a second axis and the first axis and through which a first input current flows; a second input side conductive member wound around the second axis on the first surface and has a second portion between the second axis and the first portion and through which a second input current flows; a first output side conductive member wound around the first axis on a second surface, which faces the first surface, and has a third portion which faces the first portion; and a second output side conductive member wound around the second axis on the second surface and has a fourth portion which faces the second portion.

Balun device and differential phase shifter are provided. The balun device includes a first primary coil, a first secondary coil, a second primary coil and a second secondary coil, the first primary coil having a first terminal receiving a first differential signal, and a second terminal outputting a first in-phase component, the first secondary coil having a first terminal outputting a first component orthogonal to the first in-phase component, and a second terminal coupled to AC ground, the second primary coil having a first terminal receiving a second differential signal, and a second terminal outputting a second in-phase component; the second secondary coil having a first terminal outputting a second component orthogonal to the second in-phase component, and a second terminal coupled to AC ground; phase differences between the first and second differential signals, between the first and second in-phase components, between the first and second orthogonal component are 180°.

A power amplifier circuit includes a first power amplifier, a balun, a second power amplifier, and a third power amplifier. The second and third power amplifiers each include unit bipolar transistors each including a first terminal electrically connected to a reference potential, a second terminal, and a third terminal that outputs an amplified signal; a common input terminal electrically connected to the second terminals of the transistors and receives an RF signal; a common bias terminal electrically connected to the second terminals of the transistors and receives a bias current; a common output terminal electrically connected to the third terminals of the transistors and outputs the amplified signal; and resistance elements each of which is electrically connected between the common input terminal and the second terminal of a corresponding one of the transistors and cuts a DC component of the bias current.

A Radio Frequency (RF) circuit including a receive path, a transmit path, a switching circuit, and an output configured to receive RF signals from an antenna in a receive mode of operation, and to provide RF signals to the antenna in a transmit mode of operation. The receive path is configured to be coupled between a low-noise amplifier and the output. The switching circuit is located in the receive path and is configured, in the receive mode, to selectively couple the low-noise amplifier to the output and to pass the received RF signals from the output to the low-noise amplifier. The transmit path is configured to be coupled between a power amplifier and the output, to provide, in the transmit mode, signals from the power amplifier to the output, bypassing the switching circuit, and to have, in receive mode of operation, an off-state impedance of at least 200+j*13 Ohm.

A semiconductor device includes first member that includes a switch made of a semiconductor element made from an elemental semiconductor. The first member is joined to a second member including a radio-frequency circuit including a semiconductor element made from a compound semiconductor. The switch and the radio-frequency circuit are connected by a path. The path includes an inter-member connection wire made of a metal pattern arranged on an interlayer insulating film extending from a surface of the second member to a surface of the first member or a conductive member allowing a current to flow in a direction crossing an interface where the first member and the second member are joined.

A system includes a first differential amplifier and a first transformer with a primary coil coupled to an output of the first differential amplifier and with a secondary coil coupled to a load. The system also includes a second differential amplifier and a second transformer with a primary coil coupled to an output of the second differential amplifier and with a secondary coil coupled in series with the secondary coil of the first transformer. The system also includes a tuning network coupled to a center tap node between the secondary coil of the first transformer and the secondary coil of the second transformer.

Systems, methods, and devices relate to tunable circuits for multimode power amplification. For example, a variable-gain amplification system can include an amplifier configured to provide an amplified signal and to selectively operate in at least a first gain mode and a second gain mode. The variable-gain amplification system can also include a tunable circuit configured to receive the amplified signal from the amplifier and to provide an output signal. The tunable circuit can be configured to implement a first turn ratio for the first gain mode and a second turn ratio for the second gain mode.