An impedance converter includes an insulating layer; a first wire provided on a first surface of the insulating layer and extending in a first direction; a second wire provided on a second surface of the insulating layer and extending in the first direction and face the first wire, the second surface being located on a side opposite to the first surface; a third wire provided on the first surface and extending in a second direction orthogonal to the first direction; a fourth wire provided on the second surface and extending in the second direction and face the third wire; a fifth wire provided on the first surface and extending in the second direction; and a sixth wire provided on the second surface and extending in the second direction and face the fifth wire.

A bidirectional coupler includes the following elements. A main line and a sub-line are electromagnetically coupled. First and second resistors are each grounded at one end. First and second switches connect the sub-line to the first and second resistors or a third port. A third resistor is disposed between one end of the sub-line and the first switch or between the other end of the sub-line and the second switch. When detecting an input signal, the first switch electrically connects one end of the sub-line to the other end of the first resistor and the second switch electrically connects the other end of the sub-line to the third port. When detecting a reflected signal, the first switch electrically connects one end of the sub-line to the third port and the second switch electrically connects the other end of the sub-line to the other end of the second resistor.

A signal compensation device is disclosed. The signal compensation device includes an operation circuit and a modulation circuit. The operation circuit is configured to generate a control signal according to a first data signal and a second data signal, in which the second data signal is generated according to the first data signal by a signal conversion circuit. The modulation circuit is configured to provide a loop gain according to the control signal to compensate an attenuation of the signal conversion circuit.

A power amplifier includes a 3-dB coupler which splits a first signal into a second signal and a third signal lagging behind the second signal by 90°, a carrier amplifier, a peak amplifier, and a hybrid coupler. The carrier amplifier amplifies the second signal and outputs a fourth signal when the first-signal power level is a first level or higher. The peak amplifier amplifies the third signal and outputs a fifth signal when the first-signal power level is a second level or higher, which is higher than the first level. The hybrid coupler includes a first transmission line receiving the fourth signal at its first terminal, and a second transmission line receiving the fifth signal at its first terminal and being open at its second terminal. The first transmission line outputs, from its second terminal, an amplified first signal obtained by combining the fourth and fifth signals.

This application is generally related to methods and systems for improving amplifier performance. For example, the system includes two or more gain and phase modulators. The system also includes two or more component amplifiers operably coupled to, and downstream of, the power splitter, where each of the two or more component amplifiers is operably coupled to a respective one of the two or more gain and phase modulators. The system further includes a power combiner operably coupled to, and downstream of, the two or more component amplifiers, configured to output a power signal. The system even further includes a Walsh generator configured to generate and transmit first and second Walsh codes to each of the two or more gain and phase modulators. The first Walsh code is orthogonal to the second Walsh code. A first set of the first and second Walsh codes is inverted with respect to a second set of the first and second Walsh codes.

The present disclosure is a novel utility of a software defined radio (SDR) based Distributed Antenna System (DAS) that is field reconfigurable and support multi-modulation schemes (modulation-independent), multi-carriers, multi-frequency bands and multi-channels. The present disclosure enables a high degree of flexibility to manage, control, enhance, facilitate the usage and performance of a distributed wireless network such as flexible simulcast, automatic traffic load-balancing, network and radio resource optimization, network calibration, autonomous/assisted commissioning, carrier pooling, automatic frequency selection, frequency carrier placement, traffic monitoring, traffic tagging, pilot beacon, etc.

The present disclosure is a novel utility of a software defined radio (SDR) based Distributed Antenna System (DAS) that is field reconfigurable and support multi-modulation schemes (modulation-independent), multi-carriers, multi-frequency bands and multi-channels. The present disclosure enables a high degree of flexibility to manage, control, enhance, facilitate the usage and performance of a distributed wireless network such as flexible simulcast, automatic traffic load-balancing, network and radio resource optimization, network calibration, autonomous/assisted commissioning, carrier pooling, automatic frequency selection, frequency carrier placement, traffic monitoring, traffic tagging, pilot beacon, etc.

A radio frequency (RF) front end for wireless communications, in particular for use in a half duplex (HD) and/or full duplex (FD) transceiver. The RF front end is based on a quadrature balanced power amplifier (QBPA). The RF front end includes an antenna port for outputting a transmit signal to and receiving a receive signal from an antenna, and a receive port for outputting the receive signal to a signal processing section. Further, the QBPA is configured to receive a transmit input signal at a first port, receive a cancellation input signal at a fourth port, and receive the receive signal at a second port coupled to the antenna port.

A method for transforming the impedance of a radio-frequency transmission line of a printed circuit from a first impedance value to a second impedance value, the radio-frequency transmission line being adapted to transport a radio-frequency signal at a frequency value comprised in a frequency range defined between a minimum frequency value and a maximum frequency value, wherein the following steps are envisaged:—dividing the radio-frequency transmission line into a plurality of circuit sections each one of the circuit sections including a first and a second impedance connected in parallel with each other by two circuit branches placed at a maximum distance (d.sub.max) from each other, wherein the circuit sections have respective third impedance values that gradually increase, respectively decrease, from the first impedance value to the second impedance value;—determining the maximum distance between the circuit branches in such a way as to avoid any undesired frequency values within the frequency range;—setting a fourth impedance value of one of the two impedances;—calculating a fifth impedance value of the other one of the two impedances, such that the impedance value of the circuit section is the third respective impedance value.

A sequenced transmit muting wideband power amplifier is provided that includes at least one pre-driver stage having at least a first pre-driver and a second pre-driver. A mute switch selectively establishes a communication path between the first and second pre-drivers or couples the second pre-driver to a termination resistor. A pre-driver switch selectively activates/deactivates the first and second pre-drivers. A driver stage is in communication with the pre-driver stage and includes a first driver. A final amplifier stage is in communication with the driver stage and includes at least one second driver. At least one S-NBS switch is configured to selectively activate/deactivate the first driver and second driver. A controller is configured to activate the at least one pre-driver switch, the mute switch, the at least one S-NBS switch to selectively place the amplifier in one of a transmit mode and a mute mode.