A method for biasing a power amplifier using a transmission signal having a time-varying envelope is provided. The method comprises producing a time-varying signal indicative of an amplitude of the envelope of the transmission signal and comparing the time-varying signal to a plurality of distinct threshold voltages. The method further comprises, for each of the plurality of distinct threshold voltages exceeded by the time-varying signal, providing a respective bias voltage to a respective input of a summing device and producing, using the summing device, an output bias voltage that is at least a sum of the respective bias voltages provided to the respective inputs of the summing device. The method further comprises biasing the power amplifier with the output bias voltage and amplifying the transmission signal using the power amplifier biased at the output bias voltage.

Circuits, devices and methods related to power amplification without matching network. In some embodiments, a power amplification circuit can include a power amplifier configured to amplify a signal. The power amplification circuit can further include a filter coupled to the power amplifier. The power amplifier can be further configured to operate with an impedance that is approximately same as an impedance of the filter.

The present disclosure relates to radiofrequency (RF) communications systems that may operate efficiently over a broad range of signal output levels. Electronic devices may employ amplification circuitry in the communication RF systems to provide output signal power. For example, amplification provided by external power amplifiers disposed in front-end modules may be more efficient at a higher range of output signal power, but may be inefficient at a lower range of output signal power. The disclosure relates to architectures for RF communication systems having transceivers and front-end modules that may provide power-efficient over broad ranges. Front-end modules may, for example, be managed to disable and/or enable external power amplifiers based of the output signal power. Transceivers may, for example, include internal power amplifier which may provide amplification for low output signals, and may operate as a driver to the external power amplifier of the front-end module for high output signals. Methods for managing the circuitry are also discussed.

This disclosure provides systems, methods and apparatuses for characterizing and operating a power amplifier. Before being placed into operation, output phase and output gain characteristics of the power amplifier may be determined over various operating conditions including varying two independent control signals and a supply voltage. The output phase and output gain characteristics may be stored for later retrieval. The power amplifier may be operated by determining a control signal profile for the two independent control signals based on operating conditions and radio-frequency (RF) envelope information associated with an input signal received by the power amplifier. The independent control signals may be generated in accordance with the control signal profile.

Various methods and circuital arrangements for biasing one or more gates of stacked transistors of an amplifier are presented, where the amplifier can have a varying supply voltage that varies according to a control voltage. The control voltage can be related to a desired output power of the amplifier and/or to an envelope signal of an input signal to the amplifier. Particular biasing for selectively controlling the stacked transistors to operate in either a saturation region or a triode region is also presented. Benefits of such controlling, including increased linear response of an output power of the amplifier, are also discussed.

An envelope tracking (ET) power management circuit is provided. The ET power management circuit includes an amplifier circuit(s) configured to output a radio frequency (RF) signal at a defined power level corresponding to a direct current, an alternating current, and an ET modulated voltage received by the amplifier circuit(s). The ET power management circuit can operate in a high-power ET mode when the defined power level exceeds a defined power level threshold and the RF signal is modulated to include no more than a defined number of resource blocks. The ET power management includes two ET tracker circuitries each generating a respective ET modulated voltage and two charge pump circuitries each generating a respective current. In the high-power ET mode, both charge pump circuitries are activated to each provide a reduced current to the amplifier circuit, thus helping to reduce a footprint and cost of the ET power management circuit.

Spatially combining signals may include receiving a number of RF input signals at a number of RF input connectors. At least one of the RF input signals is a variable envelope signal. A variable envelope signal is converted into two or more outphased constant envelope signals. The two or more outphased constant envelope signals are amplified. The amplified outphased constant envelope signals are radiated. At a spatial combiner aperture, the radiated amplified outphased constant envelope signals are combined to create a combined signal. The combined signal is output onto an output RF connector.

Envelope trackers providing compensation for power amplifier output load variation are provided herein. In certain configurations, a radio frequency (RF) system includes a power amplifier that amplifies an RF signal, an output detector coupled to an output of the power amplifier and that generates an output detection signal, an input detector coupled to an input of the power amplifier and that generates an input detection signal, and an envelope tracker that generates a power amplifier supply voltage for the power amplifier based on an envelope of the RF signal. The envelope tracker compensates the power amplifier for output load variation based on the output detection signal and the input detection signal.

A linear amplifier of an envelope tracking supply modulator includes a pre-driver stage circuit and an output stage circuit. The pre-driver stage circuit receives an envelope input, and generates a pre-driver output according to the envelope input. The output stage circuit receives the pre-driver output, and generates an amplifier output according to the pre-driver output. The amplifier output is involved in setting a modulated supply voltage of a power amplifier. The output stage circuit has a plurality of amplifiers, including a first amplifier and a second amplifier. When the power amplifier has a first output power level, the first amplifier is involved in setting the amplifier output, and the second amplifier is not involved in setting the amplifier output. When the power amplifier has a second output power level different from the first output power level, the first amplifier and the second amplifier are involved in setting the amplifier output.

A digital compensation system for a radio frequency (RF) power amplifier module is disclosed. The digital compensation system includes an RF power amplifier having a first input, a first output, and a first bias input, wherein the RF power amplifier is configured to receive an RF signal at the first input and generate an amplified version of the RF signal at the first output. The digital compensation system also includes compensation circuitry coupled between the first input and the first output and a bias output coupled to the RF power amplifier, wherein the compensation circuitry is configured, in response to the RF signal, to generate or adjust a bias signal at the first bias input to correct dynamic bias errors caused by amplification variations that have time constants.