A switching amplifier includes a first portion of a power stage; a second portion of a power stage; a pulse-width modulation (PWM) control loop coupled to control inputs of the first portion of the power stage; and a linear amplifier coupled to control inputs of the second portion of the power stage. The PWM control loop controls a first switch and a second switch of the first portion of the power stage. Between current terminals of the first switch and the second switch is a first signal output of the switching amplifier. The linear amplifier controls a third switch and a fourth switch of the second portion of the power stage. Between current terminals of the third switch and the fourth switch is a second signal output of the switching amplifier.

Systems and methods for isolating audio content and biometric authentication include receiving, with an audio receiver, an audio signal spanning a plurality of frequency bands, identifying a speech signal carried by a voice frequency band selected from the plurality of frequency bands, enhancing the speech signal relative to other audio content within the audio signal, and extracting a voice profile key that uniquely identifies the speech signal.

A device and method for controlling reproduction of an audio signal is provided, wherein the device is operated by means of an energy storage device. The method comprises the steps of deactivating a normal mode and activating an energy saving mode. Power consumption from the energy storage device for reproduction of the audio signal is reduced in the energy saving mode when compared to the normal mode. The method comprises reducing in the energy saving mode, a bass frequency component of a frequency spectrum of the audio signal and outputting the audio signal with reduced bass frequency component. The method further comprises ascertaining a charge state of the energy storage device and controlling the reduction in the bass frequency component based on a decrease in the charge state of the energy storage device.

A device and method for controlling reproduction of an audio signal is provided, wherein the device is operated by means of an energy storage device. The method comprises the steps of deactivating a normal mode and activating an energy saving mode. Power consumption from the energy storage device for reproduction of the audio signal is reduced in the energy saving mode when compared to the normal mode. The method comprises reducing in the energy saving mode, a bass frequency component of a frequency spectrum of the audio signal and outputting the audio signal with reduced bass frequency component. The method further comprises ascertaining a charge state of the energy storage device and controlling the reduction in the bass frequency component based on a decrease in the charge state of the energy storage device.

Disclosed are a method and apparatus for improving a signal-to-noise ratio of a microphone signal. The method includes: selecting a target microphone to be improved as a first microphone, and selecting a microphone whose signal-to-noise ratio is greater than a signal-to-noise ratio of the first microphone and exceeds a preset first threshold as a second microphone; and adding, by an adder, a voice signal of the first microphone and a voice signal of the second microphone in a case that a same voice signal is inputted, to obtain a first microphone signal whose signal-to-noise ratio has been improved.

A gain stage includes an offset cancellation loop coupled to a first amplifier. The first amplifier has a first transfer function and a first gain, and the offset cancellation loop includes a second amplifier having a second transfer function and a second gain. The second transfer function is based on an inverse of the first transfer function and the second gain based on an inverse of the first gain. When the offset cancellation loop feeds back an output signal of the first amplifier to an input of the first amplifier, a high-pass pole (or high-pass corner frequency) of the first amplifier is maintained at a constant level in spite of variations in the gain of the first amplifier. In one case, the second amplifier in the offset cancellation loop may be a simpler and lower power version of the first amplifier.

A gain stage includes an offset cancellation loop coupled to a first amplifier. The first amplifier has a first transfer function and a first gain, and the offset cancellation loop includes a second amplifier having a second transfer function and a second gain. The second transfer function is based on an inverse of the first transfer function and the second gain based on an inverse of the first gain. When the offset cancellation loop feeds back an output signal of the first amplifier to an input of the first amplifier, a high-pass pole (or high-pass corner frequency) of the first amplifier is maintained at a constant level in spite of variations in the gain of the first amplifier. In one case, the second amplifier in the offset cancellation loop may be a simpler and lower power version of the first amplifier.

An IC for power conversion includes bias circuitry that generates one or more bias voltages. An adaptive biasing circuit adaptively shifts an input signal having a negative value to a positive value. An operational transconductance amplifier (OTA) receives a supply bias current and the first and second bias voltages. The OTA has first and second input terminals coupled to the input signal and ground, respectively. The OTA has first and second transistors coupled to the first and second input terminals through first and second resistors at first and second internal nodes, respectively. Additional circuitry of the OTA is coupled to the second internal node. The additional circuitry insures that the voltage at the second internal node follows the voltage at the first internal node. The OTA generates an output current signal responsive to a differential input voltage applied across the first and second input terminals.

An IC for power conversion includes bias circuitry that generates one or more bias voltages. An adaptive biasing circuit adaptively shifts an input signal having a negative value to a positive value. An operational transconductance amplifier (OTA) receives a supply bias current and the first and second bias voltages. The OTA has first and second input terminals coupled to the input signal and ground, respectively. The OTA has first and second transistors coupled to the first and second input terminals through first and second resistors at first and second internal nodes, respectively. Additional circuitry of the OTA is coupled to the second internal node. The additional circuitry insures that the voltage at the second internal node follows the voltage at the first internal node. The OTA generates an output current signal responsive to a differential input voltage applied across the first and second input terminals.

An audio processing apparatus includes an audio input unit configured to input a plurality of audio signals, a reduction unit configured to reduce the amount of wind noise in the plurality of input audio signals, and a controller configured to control the reduction amount of the wind noise by the reduction unit based on a difference between an in-phase component and an antiphase component of the plurality of audio signals and control the speed of change of the reduction amount of the wind noise by the reduction unit based on a magnitude of the in-phase component of the plurality of audio signals. The audio processing apparatus reduces the adverse effects of the wind noise reduction process on the audio quality of the audio signals.