An RF receiver circuit configuration and design limited by conditions and frequencies to simultaneously provide steady state low-noise signal amplification, frequency down-conversion and image signal rejection. The invention provides combined circuits of an RF transceiver architecture that measure antenna reflected power relative to forward power using the error amplifier signal to adjust the gain of the variable gain amplifier in order to compensate for the mismatch between forward reflected power and forward power at the antenna in order to achieve constant radiated power. The RF receiver circuit may be implemented as one of a CMOS single chip device or as part of an integrated system of CMOS components.

Circuits and methods for achieving high linearity, high efficiency power amplifiers, including digital predistortion (DPD) and pulse cancellation in switched-state RF power amplifier systems are described.

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.

An embodiment of an amplifier includes a first amplifier with a first output terminal, a second amplifier with a second output terminal, and a plurality of microstrip transmission lines electrically connected to the amplifiers. The transmission lines include an impedance inverter line electrically connected between the first and second output terminals, and an output line electrically connected between the second output terminal and an output of the amplifier, where the output line forms a portion of an output impedance transformer. The amplifier also includes a directional coupler formed from a main line and a coupled line positioned in proximity to the main line, where the main line is formed from a portion of one of the transmission lines. The amplifier may also include a module substrate with a plurality of metal layers, where the main line and the coupled line are formed from different portions of the metal layers.

A method comprises: measuring reflected and forward power at a power amplifier output; determining if the reflected power equals to or exceeds a first level; if the reflected power is equal to or exceeds the first level, then reduce power of a power amplifier input signal; determining if a standing wave ratio at the power amplifier output equals or exceeds a second level; if the standing wave ratio at the power amplifier output equals or exceeds the second level, then reducing the power amplifier input signal power level and/or sending an alarm; determining if the power amplifier output power equals or exceeds a third level; and if the power output from the power amplifier equals or exceeds the third level, then reducing the power amplifier input signal power level until such power level is less than or equal to the third level and/or sending an alarm.

An embodiment of an amplifier includes a first amplifier with a first output terminal, a second amplifier with a second output terminal, and a plurality of microstrip transmission lines electrically connected to the amplifiers. The transmission lines include an impedance inverter line electrically connected between the first and second output terminals, and an output line electrically connected between the second output terminal and an output of the amplifier, where the output line forms a portion of an output impedance transformer. The amplifier also includes a directional coupler formed from a main line and a coupled line positioned in proximity to the main line, where the main line is formed from a portion of one of the transmission lines. The amplifier may also include a module substrate with a plurality of metal layers, where the main line and the coupled line are formed from different portions of the metal layers.

Certain aspects of the present disclosure provide a directional coupler. In certain aspects, the directional coupler generally includes a first inductor and a second inductor wirelessly coupled to the first inductor. In certain aspects, the directional coupler generally includes an input port at a first terminal of the first inductor and a transmitted port at a second terminal of the first inductor. In certain aspects, the directional coupler generally includes a coupled port at a first terminal of the second inductor and an isolated port at a second terminal of the second inductor. In certain aspects, the directional coupler generally includes a first complex impedance component directly coupled to the isolated port and a second complex impedance component directly coupled to the coupled port.

An output power control device includes: an attenuator to attenuate power of a high-frequency signal output from an oscillator; a high-frequency power amplifier to amplify the power of the high-frequency signal output from the attenuator; a monitor circuit to monitor the power of the high-frequency signal output from the high-frequency power amplifier; and a controller to control an attenuation amount of the attenuator based on the monitor signal output from the monitor circuit or based on attenuation amount setting data from a data unit. The oscillator generates the high-frequency signal in synchronization with a trigger signal. The controller starts control of the attenuation amount of the attenuator based on the attenuation amount setting data, in synchronization with the trigger signal, and, after receiving the monitor signal, the controller controls the attenuation amount of the attenuator based on the monitor signal.

This application provides an example base station for an example wireless communication network and an example method. One example base station includes a central unit and a remote radio unit (RRU). The RRU includes one or more antennas. The RRU is coupled to the central unit via one or more optical transmission fibers. Each optical transmission fiber defines a respective downlink transmission channel for transmitting a respective downlink transmission signal from the central unit to the respective antenna of the RRU. The RRU is configured to provide a respective uplink feedback signal based on the respective downlink transmission signal via an uplink feedback channel to the central unit.

An exemplary system comprises a linearizer module, a first upconverter module, a power amplifier module, a signal sampler module, and a downconverter module. The linearizer module may be configured to receive a first intermediate frequency signal and to adjust the first intermediate frequency signal based on a reference signal and a signal based on a second intermediate frequency signal. The first upconverter module may be configured to receive and up-convert a signal based on the adjusted first intermediate frequency signal to a radio frequency signal. The power amplifier module may be configured to receive and amplify a power of a signal based on the radio frequency signal. The signal sampler module may be configured to sample a signal based on the amplified radio frequency signal. The downconverter module may be configured to receive and down-convert a signal based on the sampled radio frequency signal to the second intermediate frequency signal.