A maximum current detection circuit with multiple input current ports and a maximum current port generates, on the maximum current port, a maximum current corresponding to the largest input current on one of the input current ports. The maximum current detection circuit includes multiple current mirror circuits, each controlled by one of the input currents. Each of the current mirror circuits includes outputs, each coupled to a respective one of the input current ports and the maximum current port. The current mirror circuit controlled by the largest input current becomes the dominant source for the input currents on each of the input current ports and also drives the maximum current on the maximum current port. The input currents may be single-ended or differential signals. The input currents may be respectively delayed signals of a windowing circuit in an envelope tracking circuit controlling a power amplifier of a wireless device.

An integrated circuit includes an oscillator and a power amplifier. The oscillator includes a first node, a second node, and a network of one or more reactive components coupled between the first node and the second node. The power amplifier includes a first input coupled to the first output of the oscillator, a second input coupled to the second output of the oscillator, and an output. The power amplifier includes a coarse gain control circuit, a first amplifier stage, and a second amplifier stage.

A power amplification circuit can include an input impedance matching circuit associated with one or more frequency bands of a plurality of frequency bands. The power amplification circuit can include a transistor with respective input coupled to an output of the input impedance matching circuit. The power amplification circuit can include a plurality of output impedance matching circuits. Each output impedance matching circuit can be associated with a respective frequency band of the plurality of frequency bands. The power amplification circuit can include a single pole multi-throw (SPMT) switch having an input terminal connected to an output of the transistor and a plurality of output terminals. Each output terminal of the SPMT switch can be connected to a corresponding output impedance matching circuit of the plurality of output impedance matching circuits.

A power amplification circuit can include an input impedance matching circuit associated with one or more frequency bands of a plurality of frequency bands. The power amplification circuit can include a transistor with respective input coupled to an output of the input impedance matching circuit. The power amplification circuit can include a plurality of output impedance matching circuits. Each output impedance matching circuit can be associated with a respective frequency band of the plurality of frequency bands. The power amplification circuit can include a single pole multi-throw (SPMT) switch having an input terminal connected to an output of the transistor and a plurality of output terminals. Each output terminal of the SPMT switch can be connected to a corresponding output impedance matching circuit of the plurality of output impedance matching circuits.

A multi-band power amplifier module includes at least one transmission input terminal, at least one power amplifier circuit that receives a first transmission signal and a second transmission signal through the at least one transmission input terminal, a first filter circuit that allows the first transmission signal to pass therethrough, a second filter circuit that allows the second transmission signal to pass therethrough, at least one transmission output terminal through which the first and second transmission signals output from the first and second filter circuits are output, a transmission output switch that outputs each of the first and second transmission signals output from the at least one power amplifier circuit to the first filter circuit or the second filter circuit, and a first tuning circuit that adjusts impedance matching between the at least one power amplifier circuit and the at least one transmission output terminal.

Envelope tracking power amplifiers with advanced gain shaping are provided. In certain implementations, a power amplifier system includes a power amplifier that amplifies a radio frequency (RF) signal and an envelope tracker that controls a voltage level of a supply voltage of the power amplifier based on an envelope of the RF signal. The power amplifier system further includes a gain shaping circuit that generates a gain shaping current that changes with the voltage level of the supply voltage from the envelope tracker. For example, the gain shaping circuit can include an analog look-up table (LUT) mapping a particular voltage level of the supply voltage to a particular current level of gain shaping current. Additionally, the gain shaping circuit biases the power amplifier based on the gain shaping current.

Envelope tracking systems for power amplifiers are provided herein. In certain embodiments, an envelope tracker is provided for a power amplifier that amplifies an RF signal. The envelope tracker includes an error amplifier that controls a voltage level of a power amplifier supply voltage of the power amplifier based on amplifying a difference between a reference signal and an envelope signal indicating an envelope of the RF signal. The envelope tracker further includes a multi-level switching circuit that generates an error amplifier supply voltage based on sensing a current of the error amplifier, and uses the error amplifier supply voltage to power the error amplifier.

Aspects of this disclosure relate to an acoustic wave resonator with transverse mode suppression. The acoustic wave resonator can include a piezoelectric layer, an interdigital transducer electrode, a temperature compensation layer, and a mass loading strip. The mass loading strip can be a conductive strip. The mass loading strip can overlap edge portions of fingers of the interdigital transducer electrode. A layer of the mass loading strip can have a density that is at least as high as a density of a material of the interdigital transducer electrode. The material of the interdigital transducer can impact acoustic properties of the acoustic wave resonator.

A system for adapting the voltage of a drain of a power stage includes at least two transmission paths T.sub.Xa, a transmission path comprising a resistive element (1.sub.n), a phase control module (2.sub.n), and a power stage (3.sub.n) at the output of which a radiating element (E.sub.n) is arranged, comprising at least: a device (5.sub.n) for determining the value of a reflected power P.sub.r, the value of an incident power P.sub.i in a power stage, and the ratio of the powers R, an analogue device (6.sub.n) configured so as to pulse width-modulate the difference signal, a switching cell (7.sub.n) receiving a low-power PWM signal and designed to generate a power signal PWM.sub.a that is transformed, by a low-pass filter (8.sub.n), into a bias signal for biasing the power stage in accordance with a predefined bias control law.

The present disclosure provides a method of linearization for a non-linear system, comprising: a group of steps comprising: inputting an input signal to the non-linear system; obtaining an output signal from the non-linear system in response to the input signal being input to the non-linear system; obtaining a desired signal for the non-linear system; comparing the output signal with the desired signal, to determine whether the input signal is a target signal for the non-linear system to achieve a desired performance; and in response to determining that the input signal is not the target signal for the non-linear system to achieve the desired performance, generating an updated signal in frequency domain by applying a coefficient to eliminate a difference between the output signal and the desired signal, for updating the input signal to the non-linear system. The present disclosure also provides a corresponding device, computer programs, and computer-readable storage.