An apparatus is disclosed for phase-shifting signals with a compensation circuit. In example implementations, an apparatus for phase-shifting signals includes a phase shifter having a first port and a second port. The phase shifter also includes a signal phase generator, a compensation circuit, and a vector modulator. The compensation circuit includes a first capacitor with a first capacitance and a second capacitor with a second capacitance. The first capacitance is different from the second capacitance. The signal phase generator is coupled between the first port and the compensation circuit. The vector modulator is coupled between the compensation circuit and the second port.

A semiconductor device includes a substrate, a first semiconductor layer formed over the substrate, a second semiconductor layer formed over the first semiconductor layer, a third semiconductor layer formed over the second semiconductor layer, and a gate electrode, a source electrode, and a drain electrode that are formed over the third semiconductor layer. The first semiconductor layer includes a first nitride semiconductor. The second semiconductor includes a second nitride semiconductor. The third semiconductor layer includes a third nitride semiconductor. The concentration of oxygen included in the second semiconductor layer is less than 5.0×10.sup.18 cm.sup.−3. The concentration of oxygen included in the third semiconductor layer is greater than or equal to 5.0×10.sup.18 cm.sup.−3.

The present invention discloses a power amplification apparatus having a digital pre-distortion mechanism that includes a digital pre-distortion circuit and a power amplifier. The digital pre-distortion circuit receives an original digital signal having an original real part and an original imaginary part. When a first one and a second one of the original real part and the original imaginary part are a low state voltage level and a high state voltage level, the digital pre-distortion circuit outputs a first and a second voltage levels equivalent to the low state voltage level as a first pre-distortion part and directly outputs the second one of the original real part and the original imaginary part as a second pre-distortion part to generate an input signal having an input real part and an input imaginary part each corresponding to one of the first pre-distortion part and the second pre-distortion part. The power amplifier receives the input signal to perform power amplification to generate an output signal.

A first UE may transmit, to a second subset of one or more second UEs, one or more pilot signals associated with DPD training. The first UE may receive, from a third subset of the one or more second UEs, one or more feedback messages associated with DPD training. The one or more feedback messages may be based on the one or more pilot signals. Each second UE in the third subset of the one or more second UEs may correspond to one of the one or more feedback messages. The second UE may calculate one or more DPD parameters based on the one or more feedback messages. The second UE may transmit a first signal based on the calculated one or more DPD parameters.

An amplifier device for high frequency signals, in particular a linear high frequency amplifier device, which comprises at least one input, an incoming line, a pre-distortion unit, in particular an adaptive pre-distortion unit, an amplifier unit, in particular a non-linear power amplifier unit, a transmission line, a feedback unit, and an output. The output is connected to the amplifier unit via the transmission line. In addition, the at least one input is connected to the pre-distortion unit such that two incoming branch lines are provided which are interconnected by a switching unit. A first incoming branch line of the incoming branch lines comprises a down-converter being arranged between the at least one input and the pre-distortion unit.

A curve fitting circuit, an analog predistorter, and a radio frequency signal transmitter are disclosed. Each segmentation processing circuit in the curve fitting circuit generates a to-be-processed signal according to a intercepted part of a received signal, and generates q output signals according to the to-be-processed signal. Parts intercepted by different segmentation processing circuits are not exactly the same. Each first adder circuit in the curve fitting circuit receives one signal in the q output signals of each segmentation processing circuit, and obtains one output signal of the curve fitting circuit according to a sum of received n signals.

A transceiver is disclosed which includes a transmitter and a receiver. The transmitter provides an impairment measurement signal, which is substantially similar to a transmitted communication signal except for a possible difference in phase and/or a magnitude, to the receiver. An envelope detector within the receiver provides an envelope of the impairment measurement signal to the transmitter. The transmitter determines sets of one or more filtering coefficients using the envelope of the impairment measurement signal and adjusts phases or magnitudes and/or phases of a sequences of bits used to generate the transmitted communication signal in accordance with the sets of one or more filtering coefficients to compensate for the unwanted distortion and/or the unwanted interference present within the transmitted communication signal.

An integrative software radio embodies a single multi-radio device including functionalities that are a superset of a plurality of individual discrete radio devices includes a radio frequency transmitter that integrates transmission capabilities of a plurality of discrete transmitters such that the radio frequency transmitter is configured to generate a first amalgamated waveform that is a combination of individual waveforms, each individual waveform corresponding to the transmission capabilities of its respective one of the plurality of discrete transmitters, wherein the transmission capabilities each of the plurality of discrete transmitters comprise operating characteristics different from one or more of the other discrete transmitters, wherein a waveform of a discrete transmitter comprises an adjustable electromagnetic wavefront and a proprietary waveform generation component; and a mission module communicatively coupled to the plurality of discrete transmitters and configured to alter the wavefront of at least one of the plurality of discrete transmitters to reduce interference among the at least one of the plurality of discrete transmitters without adjusting the proprietary waveform generation component.

A pulse compression radar for performing pre-distortion is provided, which has a configuration simplified in circuit structure. A radar apparatus (pulse compression radar) includes an antenna configured to externally transmit a transmission signal transmitted by a power amplifier and receive a reflection signal caused thereby as a reception signal. The radar apparatus includes a reception circuit configured to propagate this reception signal to a radar image creating module. The radar apparatus corrects beforehand, by utilizing the transmission signal (feedback signal) transmitted from the power amplifier, a transmission signal to be inputted into the power amplifier so as to cancel distortion of the transmission signal caused by amplification effect of the power amplifier. Further, a circuit where the reception signal passes and a circuit where the feedback signal passes share a part of each other.

A wideband highly linear amplifier includes a plurality of pre-distortion units for respectively linearizing digital signals of a plurality of bands, a synthesis unit for synthesizing output signals of the pre-distortion units, a single amplifier for amplifying signals outputted from the synthesis unit, distribution units for respectively separating the signals for each of the plurality of bands from the output signals of the amplifier, a plurality of inverse compensation attenuators for respectively attenuating the separated signals for each of the plurality of bands, and a feedback path for respectively feeding the attenuated signals for each of the plurality of bands back into the pre-distortion unit of the corresponding band out of the plurality of the pre-distortion units.