An audio system has an amplifier for driving an audio actuator and includes a switched-mode power supply that draws power from a power source (e.g., battery) to supply power to the amplifier, a capacitor charged by the switched-mode power supply to supply power to the amplifier, and a feed-forward compressor that performs dynamic range compression of an audio input to provide an audio output for amplification by the amplifier. The compressor includes a sidechain frequency-biasing filter that generates a frequency-biased version of the audio input that is attenuated as frequency increases which causes the compressor to decrease the compression as frequency increases. A control block limits current drawn from the battery by the switched-mode power supply independent of audio input frequency, but the frequency-biasing filter enables the amplifier to service audio power transients greater than the current-limited power supply can supply by advantageously concurrently sourcing extra power from the capacitor.

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.

An improved method of providing high burst power to audio amplifiers from limited power sources, using parallel power paths to increase system efficiency without need for a power path controller, thus utilizing a simplified circuit operation and maximizing average power available for both the amplifier and supporting circuitry.

Example embodiments provide a process that includes one or more of receiving an audio signal at a feedback compressor circuit, multiplying the received audio signal with a power feedback signal to create a product audio signal, wherein the feedback signal comprises a low-pass filtered signal, applying a power amplifier to the product audio signal, and providing the amplified product audio signal as an output signal to a speaker.

An audio system has an amplifier for driving an audio actuator and includes a switched-mode power supply that draws power from a power source (e.g., battery) to supply power to the amplifier, a capacitor charged by the switched-mode power supply to supply power to the amplifier, and a feed-forward compressor that performs dynamic range compression of an audio input to provide an audio output for amplification by the amplifier. The compressor includes a sidechain frequency-biasing filter that generates a frequency-biased version of the audio input that is attenuated as frequency increases which causes the compressor to decrease the compression as frequency increases. A control block limits current drawn from the battery by the switched-mode power supply independent of audio input frequency, but the frequency-biasing filter enables the amplifier to service audio power transients greater than the current-limited power supply can supply by advantageously concurrently sourcing extra power from the capacitor.

A class-D amplifier having an output driver with a first, second, and third driver, the output driver having a first output coupled to the first and third drivers, a second output coupled to the second driver; a sensing resistor coupled in series between the first driver and the first output; and a pulse width modulation (PWM) controller coupled to the inputs of the drivers and configured to receive an audio input signal; control a PWM generator to generate a first pulse signal and a second pulse signal based on the audio input signal and a power supply input; determine a voltage drop across the sensing resistor; and, responsive to the voltage drop being greater than a threshold, sequence control of the first pulse signal to the first driver and switch a voltage at the first driver to an increased voltage based on the voltage drop.

Amplifying a signal includes outputting an output signal from a Class D amplifier configured to operate as a current driver to a load, such as a loudspeaker, the output of the Class D amplifier controlled by a feedback loop, and, in the feedback loop: performing analog filtering using an active analog filter on an error signal that is based on the output of the Class D amplifier and a reference signal, digitizing a filtered output of the analog filter to produce a sequence of digital values, performing digital filtering on the sequence of digital values to produce a sequence of filtered digital values, and generating a pulse signal to control the output of the Class D amplifier based on the sequence of filtered digital values. The digital filter reduces a destabilizing effect of the loudspeaker's inductance. Associated circuits, systems, modules and electronic devices are disclosed.

Example embodiments provide a process that includes one or more of receiving an audio signal at a feedback compressor circuit, receiving an auxiliary attenuation signal from an auxiliary attenuation source, determining a threshold power level based on a value of the auxiliary attenuation signal, determining an output power level of the audio signal exceeds the threshold power level, combining the audio signal with the auxiliary attenuation signal from the auxiliary attenuation source and a compressed attenuation signal from the feedback compressor circuit to create a combination signal, and generating an audio output signal of the feedback compressor circuit based on the combination signal.

Various implementations include a common mode voltage controller for a self-boosting push pull amplifier. In some implementations, input signal are processed by: calculating, based upon the input signal, a maximum duty cycle to achieve a target differential in an output of the self-boosting push pull amplifier; calculating, based on the input signal, a set of control parameters associated with adjusting a common mode voltage of the output; and generating, based on the input signal, a pair of signals configured to adjust the common mode voltage of the output, wherein the pair of signals include a gain adjustment and offset based on the maximum duty cycle and the set of control parameters, and wherein the pair of signals are configured to maintain the target differential in the output of the self-boosting push pull amplifier as the common mode voltage is adjusted to a different operating point.

Example embodiments provide a process that includes one or more of receiving an audio signal at a feedback compressor circuit, determining how much to attenuate the audio signal when a power level of the audio signal exceeds a threshold power level, combining the audio signal with an auxiliary attenuation signal from an auxiliary attenuation source and a compressed attenuation signal from the feedback compressor circuit to create a combination signal, and generating an audio output signal of the feedback compressor circuit based on the combination signal.