A regulator amplifier circuit of an embodiment includes a differential amplifier circuit, an nMOS transistor, and a pMOS transistor. The differential amplifier circuit includes a differential circuit and a transistor. The differential circuit includes a differential MOS transistor circuit, and the transistor includes a gate voltage controlled by the differential circuit. The nMOS transistor includes a drain connected to a drain on minus side of the differential MOS transistor, and a gate connected to a source of the transistor. The nMOS transistor operates in a weak inversion region. The pMOS transistor includes a source connected to a source of the nMOS transistor, and a drain connected to a voltage lower than a source voltage of the nMOS transistor. The pMOS transistor operates in the weak inversion region.

A regulator amplifier circuit of an embodiment includes a differential amplifier circuit, an nMOS transistor, and a pMOS transistor. The differential amplifier circuit includes a differential circuit and a transistor. The differential circuit includes a differential MOS transistor circuit, and the transistor includes a gate voltage controlled by the differential circuit. The nMOS transistor includes a drain connected to a drain on minus side of the differential MOS transistor, and a gate connected to a source of the transistor. The nMOS transistor operates in a weak inversion region. The pMOS transistor includes a source connected to a source of the AMOS transistor, and a drain connected to a voltage lower than a source voltage of the nMOS transistor. The pMOS transistor operates in the weak inversion region.

An audio reproduction apparatus is shown and includes an amplifier with a power amplification stage having transistors in a push-pull arrangement. A bias generator biases the transistors with a standing current. A processor receives a data stream comprising digital samples of an analog audio signal and analyzes the peak level of each group. It then determines the appropriate standing currents to maintain Class A operation of the power amplification stage given the peak levels of each of the groups. A digital to analog converter produces an analog input signal for the input stage of the amplifier from the data stream. A feedforward path between the processor and the bias generator allows the standing current to be adjusted prior to the arrival of the analog input signal in the power amplification stage.

A communication device includes a power amplifier that generates power signals according to one or more operating bands of communication data, with the amplitude being driven and generated in output stages of the power amplifier. The final stage can include an output passive network that suppresses suppress an amplitude modulation-to-phase modulation (AM-PM) distortion. During a back-off power mode a bias of a capacitive unit of the output power network component can be adjusted to minimize an overall capacitance variation. A output passive network can further generate a flat-phase response between dual resonances of operation.

An audio reproduction apparatus is shown and includes an amplifier with a power amplification stage having transistors in a push-pull arrangement. A bias generator biases the transistors with a standing current. A processor receives a data stream comprising digital samples of an analog audio signal and analyzes the peak level of each group. It then determines the appropriate standing currents to maintain Class A operation of the power amplification stage given the peak levels of each of the groups. A digital to analog converter produces an analog input signal for the input stage of the amplifier from the data stream. A feedforward path between the processor and the bias generator allows the standing current to be adjusted prior to the arrival of the analog input signal in the power amplification stage.

A communication device includes a power amplifier that generates power signals according to one or more operating bands of communication data, with the amplitude being driven and generated in output stages of the power amplifier. The final stage can include an output passive network that suppresses an amplitude modulation-to-phase modulation (AM-PM) distortion. During a back-off power mode a bias of a capacitive unit of the output power network component can be adjusted to minimize an overall capacitance variation. The output passive network can further generate a flat-phase response between dual resonances of operation.