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.

A radio frequency (RF) front-end circuit is provided. A power management circuit is configured to output a first modulated voltage, a second modulated voltage, a first bias voltage, and a second bias voltage via a first voltage port(s), a second voltage port(s), a first bias voltage port(s), and a second bias voltage port(s), respectively. An amplifier circuit(s) is configured to amplify an RF signal based on a selected modulated voltage and a selected bias voltage outputted by a selected voltage port and a selected bias voltage port, respectively. The power management circuit can be controlled to dynamically increase the selected bias voltage at the selected bias voltage port in case the selected bias voltage drops below a defined bias voltage threshold. As such, it may be possible to maintain the selected bias voltage at a desirable level, thus enabling the amplifier circuit(s) to operate with improved linearity and efficiency.

Apparatus and methods for programmable low dropout regulators for radio frequency (RF) electronics are provided herein. In certain configurations, a power amplifier system includes a multi-stage power amplifier that amplifies a radio frequency signal and includes a driver stage and an output stage. The power amplifier system further includes an envelope tracker that controls a supply voltage of the output stage in relation to an envelope of the radio frequency signal, and a programmable low dropout regulator that includes an output that provides a programmable supply voltage to the driver stage. The programmable low dropout regulator includes an output capacitor electrically connected to the output, a regulation transistor having a drain electrically connected to the output, and an alternative discharge circuit that discharges the output capacitor in response to programming the programmable supply voltage from a high voltage level to a low voltage level.

A power supply modulator includes: a linear regulator; a switching regulator; and a mode-based connection circuit. The mode-based connection circuit includes a coupling circuit configured to drop an output signal of the linear regulator by a target coupling voltage in an envelope tracking (ET) modulation mode; and a coupling voltage management circuit configured to monitor a coupling voltage of the coupling circuit in another modulation mode, and selectively apply a voltage to the coupling voltage based on a monitoring result such that the coupling voltage is maintained at the target coupling voltage.

An amplifier generate harmonic noise or nuisance signals when the amplifier enters into a nonlinear amplification event. The harmonic noise or nuisance signals are spurious and a tagging circuit may tag them as such so they bypass signal processing logic and provide the same to a downstream hardware device that skips the signals tagged as spurious. The system uses a spurious signal detector and a comparator to identify nonlinear amplification events containing harmonic noise below an amplitude threshold that indicates the harmonic noise or nuisance signals as spurious to the downstream hardware device. Typically, the system is incorporated into an electronic warfare system such that the downstream hardware device effectuates countermeasures for a manned or unmanned platform.

A pre-distorter that both accurately compensates for the non-linearities of a radio frequency transmit chain, and that imposes as few computation requirements in terms of arithmetic operations, uses a diverse set of real-valued signals that are derived from separate band signals that make up the input signal. The derived real signals are passed through configurable non-linear transformations, which may be adapted during operation, and which may be efficiently implemented using lookup tables. The outputs of the non-linear transformations serve as gain terms for a set of complex signals, which are functions of the input, and which are summed to compute the pre-distorted signal. A small set of the complex signals and derived real signals may be selected for a particular system to match the classes of non-linearities exhibited by the system, thereby providing further computational savings, and reducing complexity of adapting the pre-distortion through adapting of the non-linear transformations.

According to some example embodiments, an apparatus includes a buck-boost converter, a first buck converter connected at an output terminal of the buck-boost converter, a second buck converter connected at the output terminal of the buck-boost converter, a first LA including a first supply voltage input connected to the output terminal of the buck-boost converter, and an output terminal connected to an output terminal of the first buck converter, where the first LA is configured to provide a first modulated supply voltage to a first PA of a first transmitter, and a second LA including a second supply voltage input connected to the output terminal of the buck-boost converter, and an output terminal connected to an output terminal of the second buck converter, where the second LA is configured to provide a second modulated supply voltage to a second PA of a second transmitter.

Various embodiments disclose a method and a device including: an antenna, a switching regulator, communication chip including an amplifier and a linear regulator operably connected to the amplifier and the switching regulator, the communication chip configured to transmit a radio-frequency signal from the electronic device through the antenna, and control circuitry configured to control the communication chip such that the linear regulator provides the amplifier with a voltage corresponding to an envelope of an input signal input to the amplifier, the input signal corresponding to the radio-frequency signal.

A multimode envelope tracking (ET) circuit and related apparatus is provided. The multimode ET circuit is configured to provide an ET voltage(s) to an amplifier circuit(s) for amplifying a radio frequency (RF) signal(s) that may correspond to a wider range of modulation bandwidth. In this regard, the multimode ET circuit is configured to switch dynamically and opportunistically between different operation modes based on the modulation bandwidth of the RF signal(s). In examples discussed herein, the multimode ET circuit is configured to support a single amplifier circuit in a high-modulation-bandwidth mode and an additional amplifier circuit(s) in a mid-modulation-bandwidth mode and a low-modulation-bandwidth mode. By switching dynamically and opportunistically between different operation modes, it may be possible to reduce undesired series resonance that may cause distortion in the ET voltage(s), thus helping to improve efficiency and performance of the amplifier circuit(s) supported by the multimode ET circuit.

An envelope tracking system having delay compensation circuitry is disclosed. The envelope tracking system includes transmit circuitry configured to receive an input transmit signal, a gain control signal, and delay compensation values. The envelope tracking system is further configured to generate an envelope tracking signal based on the input transmit signal, the gain control signal, and the delay compensation values, and generate an output transmit signal based on the input transmit signal. The envelope tracking system also includes a power amplifier configured to generate an amplified transmit signal based on the output transmit signal and an operating voltage. The envelope tracking system further includes an envelope tracking integrated circuit configured to control the operating voltage based on the envelope tracking signal. The delay compensation circuitry is configured to generate the delay compensation values based on a peak-to-average ratio of a given modulation type and the gain control signal.