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.

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 differential amplifier generates an output voltage waveform exhibiting a slew rate over a rise time. The amplifier is powered from a dc voltage input and includes a set of differential pairs having a bias current flowing therethrough and a Miller compensation capacitance. A comparator functions to compare a voltage at the dc voltage input against a reference voltage in order to detect when the voltage drops below the reference voltage. A gain stage controls the gain of the differential amplifier and a bias current control circuit controls the bias current of the differential amplifier. In response to the detection by the comparator of the voltage dropping below the reference voltage, the gain stage and the bias current control circuit decrease the gain of the amplifier and jointly decrease the bias current in order to maintain a value of the rise time.

A solid state power amplifier uses a Doherty power amplifier that can be implemented as a monolithic microwave integrated circuit. By adjusting the DC bias of the amplifying stages in each branch of the Doherty amplifier, the output power, linearity, and DC power can be adjusted to provide a specified output, where the specification for the output can include the maintaining of desired DC power and linearity. The Doherty power amplifier can be used in a satellite payload or other application utilizing solid state power amplifiers, while providing the proper amount of RF output power and DC power. A single amplifier can have its bias levels adjusted for different output levels, helping to minimize the number of designs that are required for a given satellite payload, reducing the variety of parts in a satellite payload.

A power amplifier (PA) circuit includes a circuit for generating a supply voltage at an upper voltage rail for a power amplifier (PA). The circuit includes a DC-to-DC converter for generating a voltage from which the supply voltage is generated; a linear amplifier for sourcing or sinking current to or from the upper voltage rail via a capacitor for performing fine adjustment of the supply voltage; a first switching device coupled between an output of the linear amplifier and a lower voltage rail to selectively assist the linear amplifier sink current through the capacitor to deal with actual or anticipated transient response of the supply voltage; and a second switching device coupled between the upper voltage rail and the lower voltage rail to selectively discharge the capacitor in response to actual or anticipated transient response of the supply voltage.

There are disclosed various methods and apparatuses for providing power to a set of power amplifiers. In some embodiments the method comprises obtaining first transmission parameters associated with a first transmit signal, selecting one or more output voltage values on the basis of the first transmission parameters, controlling a multi-level power source to generate one or more output voltages on the basis of the one or more output voltage values, multiplexing based on the first transmit signal between two or more of the output voltages and a first supply voltage terminal of a first power amplifier, and amplifying the first transmit signal with the first power amplifier.

A source follower with an input node and an output node includes a first transistor, a second transistor, and a DC (Direct Current) tracking circuit. The first transistor has a control terminal, a first terminal coupled to a first node, and a second terminal coupled to a second node. The second transistor has a control terminal, a first terminal coupled to a ground voltage, and a second terminal coupled to the first node. The DC tracking circuit sets the second DC voltage at the second node to a specific level. The specific level is determined according to the first DC voltage at the first node. The output node of the source follower is coupled to the first node.

The invention relates to a broadband high power amplifier that comprises a signal input adapted to receive an input signal, at least one amplifier stage adapted to amplify the received input signal, a signal output adapted to output the signal amplified by the at least one amplifier stage as an output signal, a monitoring unit adapted to monitor signal characteristics of the input signal and the output signal and a control unit adapted to operate the at least one amplifier stage at an optimal operating point depending on the current signal characteristics monitored by said monitoring unit.

Signal processing is applied to a digital audio input signal to provide an analog audio output signal using a switching converter circuit driven by a pulse-width-modulated (PWM) signal. The analog audio output signal is sensed to provide an analog feedback signal. The signal processing that is applied includes: converting the digital audio input signal to producing an analog replica; producing an analog error signal indicative of a difference between the analog replica of the digital input signal and the analog feedback signal; converting the analog error signal to produce a digital error signal; digitally filtering the digital error signal to produce a filtered digital error signal; and generating the PWM signal from the filtered digital error signal.

A class D audio amplifier includes a modulator for receipt of an audio signal and converting the audio signal into a modulated audio signal having a predetermined carrier frequency. The class D audio amplifier additionally includes an output stage having a plurality of power transistors coupled in cascade between a first DC supply voltage and a second DC supply voltage, and a plurality of gate drivers configured to generate respective modulated gate drive signals to the plurality of power transistors. A controller is configured to adjust a level of a first modulated gate drive signal applied to a first power transistor of the output stage based on a level of the audio signal.