An active noise source apparatus includes a pair of a first and second switched-biased noise amplifier branches (22, 23). A directional coupler (24) having a pair of input ports (3, 4) connected to combine the noise outputs from the first and second switched-biased noise amplifiers. One output port (4) of the directional coupler (24) is connected to a matched termination (Rtermination) and another output port (2) of the directional coupler (24) is connected to an output (25) of the active noise source.

An output power stabilization circuit includes: a first variable attenuator for attenuating a high-frequency signal inputted thereto; a second variable attenuator for attenuating the high-frequency signal outputted from the first variable attenuator; an output power detection circuit for monitoring the high-frequency signal outputted from the second variable attenuator and outputting an output power detection signal; a temperature monitoring circuit for outputting a temperature monitoring signal; a control circuit for outputting a first control signal for controlling the attenuation amount in the first variable attenuator and a second control signal for controlling the attenuation amount in the second variable attenuator, based on an output power setting signal and the temperature monitoring signal, by referring to previously stored table data; and an attenuation amount setting circuit for making comparison between the first control signal and the output power detection signal and outputting a first attenuation amount adjustment signal for adjusting the attenuation amount in the first variable attenuator.

An approach to predistortion of a first set of signals for an antenna array allows beam-steering without corrupting spectrum away from the main beam and where other users may be located. In some implementations, the predistorter uses fewer than one predistorter per signal (i.e., per power amplifier or per antenna), and/or has the computational complexity of such fewer predistorters, to generate predistortions of the first set of signals for amplification and transmission via the antenna array.

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 wide band directional coupler is disclosed. The coupler includes a main transmission line connected between an input port and an output port; and a coupling transmission line having a first length and connected between a coupling port and an isolation port, wherein the coupling transmission line is coupled to the main transmission line through a coupling capacitive connection and a mutual inductive connection, wherein at least a distance between the main transmission line and the coupling transmission line varies along the first length of the coupling transmission line such that any one of a capacitance value of the capacitive connection and an inductance value of the inductive connection is characterized by a relatively low value, wherein a coupling factor of the wide band directional couple remains substantially constant throughout an operating frequency band of the wide band directional coupler.

A transmission chain receives an incident signal to be transmitted having a first power and a first bandwidth. A first modulator frequency shifts a first signal derived from the incident signal to generate a first shifted signal at a modulation output. A power amplifier coupled to the modulation output amplifies an intermediate signal to generate an amplified output signal. A predistortion-signal-generating circuit generates, from the incident signal and from the amplified output signal in a second bandwidth that is larger than the first bandwidth, a predistortion signal having a second power lower than the first power. A second modulator frequency shifts a second signal derived from the predistortion signal to generate a second shifted signal for combination with the first shifted signal at said modulation output to produce the intermediate signal.

Aspects of this disclosure relate to systems and methods of performing dynamic impedance tuning. Certain aspects may be performed by or include a dynamic impedance matching network. The dynamic impedance matching network can determine a desired output power for a power amplifier, true power information for the power amplifier, and an output power delivered to a load by the power amplifier. In addition, the dynamic impedance matching network can determine whether the output power satisfies the true power information. Responsive to this determination, the dynamic impedance matching network may modify a load line impedance for the power amplifier using an impedance tuning network.

Envelope trackers providing compensation for power amplifier output load variation are provided herein. In certain configurations, a radio frequency (RF) system includes an antenna, a power amplifier that receives a radio frequency signal and outputs an amplified radio frequency signal to the antenna, a plurality of detectors coupled to the power amplifier and operable to generate a plurality of detection signals, and an envelope tracker that controls a supply voltage of the power amplifier based on an envelope of the radio frequency signal. The envelope tracker processes the plurality of detection signals to generate a load variation detection signal indicating a change in an output load of the power amplifier arising from a change in a voltage standing wave ratio (VSWR) of the antenna. Additionally, the envelope tracker adjusts a gain of the power amplifier based on the load variation detection signal.

In one embodiment an amplifier circuit is disclosed. The amplifier circuit comprises an amplifying device configured to amplify a radiofrequency signal, the amplifying device having an output dynamic range; a supply modulator configured to modulate a supply voltage supplied to the amplifying device when an output of the amplifying device is within a first region of the output dynamic range; a tuneable matching network coupled to an output of the amplifying device; and a load controller configured to control the tuneable matching network, when the output of the amplifying device is within a second region of the output dynamic range, and thereby modulate the load to which the output of the amplifying device is applied.

A power amplifier with adjustable voltage standing wave ratio is described which comprises an amplifier unit, a coupler configured to obtain an incident power and a coupled reflected power, and a power control unit. The power control unit is configured to control the amplifier unit. The power control unit has two power detectors configured to provide actuating variables which correspond to the incident power and the reflected power, respectively. The power control unit comprises two digital potentiometers which are configured to variably weight the actuating variables wherein the power control unit is configured to determine a control variable for the amplifier unit based on the actuating variables such that a predetermined power level related to a set value of the voltage standing wave ratio is not exceeded by the incident power and/or the reflected power. Further, a radio frequency electronic device and a method are described.