Beamforming channels of a satellite are calibrated using a low power, spread spectrum calibration signal. The power of the calibration signal is below the noise level of a user signal in an active channel, allowing channels to be calibrated while active. When calibrating the transmit side circuitry, a two-stage calibration can be used, first calibrating the output hybrid matrix, then calibrating the whole of the transmit side. To improve performance, the dwell time spend calibrating a channel can be based on the power of the user signal in the channel. A transmit probe can be used to inject a calibration signal into the receive antennae and a receive probe can be used to extract the calibration signal from the transmit antennae. To reduce frequency of calibrations, the calibrations can be based on path-to-path differences. These techniques are also applied to multiport amplifiers (MPAs).

An amplifier circuit for compensating an output signal provided at an output of the amplifier circuit comprises a cascade of sub-amplifiers. Each sub-amplifier of the cascade contributes to a respective part of the output signal. The cascade of sub-amplifiers comprises an end sub-amplifier and at least one preliminary sub-amplifier. At least one error correction block is coupled to apply feedforward error correction to an output of one of the at least one preliminary sub-amplifier.

A balanced amplifier system having input and output quadrature couplers or equivalents thereof and two amplifiers there between. An RF signal is presented to a first input of an input quadrature coupler such that an amplified RF signal is output at a first output of the output quadrature coupler. A RF control signal is presented to a second input of the quadrature coupler such that an amplified control signal is outputted at the other output of the output quadrature coupler. The system is configured to reflect the amplified signal back into the second port of the output quadrature coupler in order to vary an impedance seen by the amplifiers of the balanced amplifier.

Systems and apparatuses are disclosed that include an RF generator configured to generate RF signals having a wavelength. Amplifiers are configured to receive and amplify the RF signals from the RF generator and are separated from each other by a separation distance in a range between about 0.2 times the wavelength and about 10.0 times the wavelength. A power management system is configured to control one or more of the amplifiers based on information received that is associated with the RF signals.

A multistage linear power amplifier receiving an input signal. The multistage linear power amplifier comprises a plurality of Class-AB amplifiers connected in a cascade configuration. The plurality of Class-AB amplifiers amplifies the input signal to generate an amplified input signal. At least one of the plurality of Class-AB amplifiers is biased such that the multistage linear power amplifier emulates a Class-C amplifier.

A directional coupler includes a main line through which a first signal in a first frequency band and a second signal in a second frequency band pass from a first port to a second port, a sub-line electromagnetically coupled to the main line and having a third port and a fourth port, the third port outputting a first coupled signal corresponding to the first signal and a second coupled signal corresponding to the second signal, a first termination circuit connected to the fourth port and used in outputting the first coupled signal, a second termination circuit connected to the fourth port and used in outputting the second coupled signal, and a first filter circuit disposed between the fourth port and the first termination circuit, wherein the first filter circuit has frequency characteristics allowing the first coupled signal to pass therethrough and attenuating the second coupled signal.

This disclosure relates generally to Doherty amplifiers. In one embodiment, a Doherty amplifier includes an RF input of the Doherty amplifier for receiving a radio frequency (RF) signal, a main amplifier coupled to the RF input, and an auxiliary amplifier coupled to the RF input. A phase lag component connected between the RF input and one of either the main amplifier or the auxiliary amplifier and a phase lead component connected between the RF input and another one of either the main amplifier or the auxiliary amplifier. In some embodiments, the phase lead and phase lag components ensure that the split signals output from the main and auxiliary amplifier are recombined in phase throughout a frequency band.

Disclosed in the present invention are a high-bandwidth load modulation power amplifier, comprising a main-path power amplifier, an auxiliary-path power amplifier, a quadrature coupler, a main-path radio frequency signal matching network, an auxiliary-path radio frequency signal matching network and an output combined-path radio frequency signal matching network. When an input of a radio frequency signal is received, the quadrature coupler divides the input radio frequency signal into two paths of radio frequency signals, which have a 90-degree phase difference therebetween, wherein the radio frequency signal, which has a +45-degree phase, enters the main-path power amplifier, and the radio frequency signal, which has the ?45-degree phase, enters the auxiliary-path power amplifier; and the output combined-path radio frequency signal matching network synthesizes a main-path signal and an auxiliary-path signal and then outputs a radio frequency signal.

The present invention relates to a four-way Doherty amplifier. The invention further relates to a mobile telecommunications base station.

The invention proposes a new Doherty combiner topology that allows peak efficiencies to be reached at deeper back-off levels than conventional Doherty combiners.

An inverted symmetrical four-stage Doherty amplifier is disclosed. The Doherty amplifier includes a carrier amplifier and a plurality of peak amplifiers. Outputs of the carrier amplifier and the peak amplifiers are provided to the combining unit through the offset unit including offset transmission lines each connected with the carrier amplifier and the peak amplifiers. The offset transmission lines have characteristic impedance and electrical lengths equal to each other such that the impedance seeing the amplifiers at the ends of the offset transmission lines become substantially short-circuited.