Average power tracking (APT) systems with fast transient settling are disclosed. In certain embodiments, an APT system is used to provide a power amplifier supply voltage to a power amplifier that amplifies a radio frequency (RF) signal. The APT system controls the power amplifier supply voltage to track an average power of the RF signal, and generates a first regulated voltage based on a first average power tracking voltage level and a second regulated voltage based on a second average power tracking voltage level. The APT system includes a DC switch configured to receive the first regulated voltage and the second regulated voltage, and operable to change state to transition the power amplifier supply voltage from the first average power tracking voltage level to the second average power tracking voltage level.

Average power tracking (APT) systems with fast transient settling are disclosed. In certain embodiments, an APT system is used to provide a power amplifier supply voltage to a power amplifier that amplifies a radio frequency (RF) signal. The APT system controls the power amplifier supply voltage to track an average power of the RF signal, and includes a DC-to-DC converter that is assisted by an error amplifier in transitioning from one power amplifier supply voltage level to another power amplifier supply voltage level. Thus, the combination of a DC-to-DC converter with a fast changing error amplifier can swing enough AC voltage with a low enough slew rate to be able to rapidly transition the power amplifier supply voltage from one APT voltage level to another APT voltage level.

Power amplifier systems with non-linear antenna impedance for load compensation are provided. In certain embodiments, a method of power amplification in a mobile device is provided. The method includes generating a radio frequency input signal using a transceiver, amplifying the radio frequency input signal to generate a radio frequency output signal using a power amplifier, and transmitting the radio frequency output signal using an antenna, including compensating the power amplifier for a change in output load in response to a change in signal power using a non-linear impedance versus output power characteristic of the antenna.

Disclosed are a radiofrequency power amplifier module having high linearity and power-added efficiency and an implementation method. The radiofrequency power amplifier module comprises a bias circuit, a linearization circuit, and a power amplifier circuit. The power amplifier circuit is connected to the linearization circuit. The linearization circuit is connected to the bias circuit. The bias circuit is connected to the power amplifier circuit. In the present invention, the linearization circuit is utilized to capture a radiofrequency signal inputted from a radiofrequency signal input end of the power amplifier circuit, the captured radiofrequency signal is fed back to the bias circuit, a corresponding bias current is generated by the bias circuit on the basis of the radiofrequency signal fed back, and the bias current is inputted to the power amplifier circuit, thus increasing the linearity and power-added efficiency of an output signal of the radiofrequency power amplifier.

A method and system for controlling the switching power supply in a car audio system. The system includes a circuit that detects when the signal voltage is approaching the power supply voltage rails, that is, circuit anticipates the conditions that cause “clipping” of the signal. In response to detecting the pre-clipping condition, the circuit boosts the power supply. Additionally, the inventive system includes a holding circuit for sustaining the boosted power supply for a predetermined period of time. Thus, the power is boosted as needed and remains on for a period of time thereby preventing frequent, repetitive activation of the power supply.

The present disclosure provides an audio amplifier circuit, including: a modulator circuit configured to modulate an audio input signal into a pulse width modulation (PWM) signal; a switch stage circuit configured to receive the PWM signal and amplify the PWM signal; a demodulator circuit configured to receive and demodulate the amplified PWM signal to obtain a demodulated audio signal, and to output the demodulated audio signal to a speaker; and a feedback circuit configured to feed back the demodulated audio signal output by the demodulator circuit, and to output a feedback signal to an input end of the modulator circuit. Here, the feedback circuit includes an analog-to-digital converter and a loop filter. The switch stage circuit includes a driver and two gallium nitride (GaN) field effect transistors (FETs).

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.

An amplifier system includes an output circuit, a processor circuit, a feedback circuit, and a controller circuit. The output circuit outputs an output signal and returns a digital output feedback signal. The processor circuit receives a filtered error audio signal and outputs a pulse width modulation control signal to the output circuit. An addition unit of the feedback circuit adds the negative value of the digital output feedback signal to the digital input signal to obtain the error audio signal. A variable filter unit of the feedback circuit filters the error audio signal and outputs the filtered error audio signal. A compensation unit of the variable filter unit changes the gain characteristics of the variable filter unit. The controller circuit adjusts one or more parameters of the compensation unit according to a pre-compensation signal so as to change the gain characteristics of the variable filter unit.

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.

Disclosed are a radiofrequency power amplifier module having high linearity and power-added efficiency and an implementation method. The radiofrequency power amplifier module comprises a bias circuit, a linearization circuit, and a power amplifier circuit. The power amplifier circuit is connected to the linearization circuit. The linearization circuit is connected to the bias circuit. The bias circuit is connected to the power amplifier circuit. In the present invention, the linearization circuit is utilized to capture a radiofrequency signal inputted from a radiofrequency signal input end of the power amplifier circuit, the captured radiofrequency signal is fed back to the bias circuit, a corresponding bias current is generated by the bias circuit on the basis of the radiofrequency signal fed back, and the bias current is inputted to the power amplifier circuit, thus increasing the linearity and power-added efficiency of an output signal of the radiofrequency power amplifier.