An amplification circuit includes a switch circuit, an amplifier, and a control circuit. The switch circuit has a first terminal coupled to a radio frequency signal input terminal or a system voltage terminal, a second terminal coupled to an input terminal of the amplifier, and a control terminal configured to receive a control signal. The amplifier amplifies a radio frequency signal. The control circuit generates the control signal according to a driving current generated by the amplifier. When the control circuit determines that the amplifier operates in a high power mode, the control circuit controls the control signal to adjust a conducting level between the first terminal and the second terminal of the switch circuit according to the intensity of the driving current.

An audio device is adapted to receive and process a digital audio signal and output an analog audio signal. The audio device includes an adder, a digital-to-analog conversion circuit, an amplifying circuit, a voltage detecting circuit and an offset compensating circuit. The voltage detecting circuit detects a supply voltage received by the amplifying circuit. The offset compensating circuit generates a DC offset compensation value according to the supply voltage. The adder adds the digital audio signal and the DC offset compensation value to output an added signal. The digital-to-analog conversion circuit converts the added signal into a converted analog audio signal. The amplifying circuit amplifies the converted analog signal to output an amplified analog signal. Accordingly, the audio device can reduce pop noise caused by a DC offset.

A power amplifier module includes a power amplifier including an amplifier including an amplifying transistor configured to amplify an input signal, and output an output signal, and a bias circuit including a bias transistor configured to provide a bias current to the amplifying transistor; and a controller configured to provide a control current to the bias transistor, wherein the controller is configured to vary the control current based on a temperature of the amplifying transistor.

A system may include a Class-D stage comprising a first high-side switch coupled between a supply voltage and a first output terminal of the Class-D stage, a second high-side switch coupled between the supply voltage and a second output terminal of the Class-D stage, a first low-side switch coupled between a ground voltage and the first output terminal, and a second low-side switch coupled between the ground voltage and the second output terminal. The system may also include current sensing circuitry comprising a first sense resistor coupled between the first low-side switch and the ground voltage, such that an output current through a load coupled between the first output terminal and the second output terminal causes a first sense voltage proportional to the output current across the first sense resistor when the first low-side switch is activated. The current sensing circuitry may also include a second sense resistor coupled between the second low-side switch and the ground voltage, such that an output current through the load causes a second sense voltage proportional to the output current across the second sense resistor when the second low-side switch is activated. The system may also include measurement circuitry configured to measure the first sense voltage and the second sense voltage to determine the output current.

Embodiments relate to sensing a current provided by a power supply circuit. The current sensing circuit includes a sense transistor for sensing the current provided by a main transistor, a driver for controlling a bias provided to the sense transistor and the main transistor, and a sense resistor for converting the sensed current to a voltage value. Moreover, the current sensing circuit includes a controller that modifies at least one of: (a) a resistance of the main transistor by adjusting the bias voltage provided by the driver, (b) a gain ratio between a load current and a sensing current by adjusting a number of individual devices that are active in the sense transistor, and (c) a resistance of the sense resistor.

The disclosure presents a method and an amplifier system for minimizing variation in an acoustical signal caused by variation in gain of an amplifier, comprising a battery for providing a supply voltage to the amplifier, a digital signal processor for providing the acoustical signal to the amplifier, a controller unit receiving an enablement signal when the supply voltage is in an offset mode, and based on the enablement signal requesting a measured voltage during a time period, and a first analog-to-digital converter configured for measuring the supply voltage to the amplifier when receiving the request from the controller unit or the first analog-to-digital converter is configured for measuring the supply voltage to the amplifier continuously, and where variations in the measured voltage relates to variations in the supply voltage during the time period. Furthermore, the controller unit is configured to predict offset modes (i.e. changes) in the supply voltage based on the enablement signals and a fitting of the measured voltages, and wherein the controller unit is configured to generate a compensating signal based on the fitting and transmit the compensating signal to the digital signal processor, the digital signal processor is then configured to minimize variation in the acoustical signal at the output of the amplifier by compensating the variation in gain of the amplifier based on the compensating signal.

The technology described in this document can be embodied in an audio power amplifier that includes a first channel and a second channel. Each of the first channel and the second channel includes an input to receive an input signal, a pair of switching devices, drive circuitry for driving the pair of switching devices to produce a signal, and an output filter to filter the signal from the pair of switching devices. The output filter is configured to provide the filtered signal to an audio load. Each of the first channel and the second channel includes a voltage feedback loop to provide a voltage of the filtered signal to a voltage controller of the audio power amplifier, and a current feedback loop to provide a current of the filtered signal to a current controller of the audio power amplifier. The audio power amplifier includes a summer for combining the input of the first channel and the input of the second channel when an output of the first channel is connected to an output of the second channel.

A system may include a charge pump configured to boost an input voltage of the charge pump to an output voltage greater than the input voltage, a current mode control loop for current mode control of a power amplifier powered by the output voltage of the charge pump, and a controller configured to, in a current-limiting mode of the controller, control an output power of the charge pump to ensure that an input current of the charge pump is maintained below a current limit, control the power amplifier by placing the power amplifier into a high-impedance mode during the current-limiting mode, and control state variables of a loop filter of the current mode control loop during the current-limiting mode.

A current source and/or current sink digital-to-analog converter (DAC) includes a DAC circuit that converts a digital code to an analog current or voltage signal, an optional transconductance circuit that converts a voltage output of the DAC circuit into a current signal, and an output circuit that amplifies a current output of the DAC circuit or optionally amplifies a current output of the transconductance circuit to set a desired high current output for application to an output of the current source and/or current sink DAC. A power supply control current may be coupled to a power supply circuit that supplies power to the output circuit of the current source and/or current sink DAC. The power supply control current adjusts the output of the power supply circuit to cause the current source and/or current sink DAC to operate at a higher power efficiency.

An offset-cancellation circuit having a first amplification stage with a gain of the first amplification stage and configured to receive an offset voltage of a first amplifier. A storage element is configured to be coupled to and decoupled from the first amplification stage and configured to store a potential difference output by the first amplification stage. The potential difference is determined by the offset voltage of the first amplifier and the gain of the first amplification stage. A second amplification stage is coupled to the storage element and configured to receive the potential difference from the storage element when the storage element is decoupled from the first amplification stage and configured to deliver an offset-cancellation current. The offset-cancellation current is determined by the potential difference and a gain of the second amplification stage.