A method for using driver circuitry to drive a load having an unknown impedance magnitude includes (a) in a configuration mode of the driver circuitry, determining a required power supply voltage for a driver stage to drive the load, and (b) in a driving mode of the driver circuitry, (1) driving the load via the driver stage in response to an input signal, and (2) controlling a power supply to provide the required power supply voltage to the driver stage as a static voltage, while driving the load via the driver stage in response to the input signal.

A signal processing system may include a modulation stage configured to generate a modulated input signal, an open-loop switched mode driver coupled to the modulation stage and configured to generate an output signal from the modulated input signal, a voltage regulator configured to generate a supply voltage that supplies electrical energy to the open-loop switched mode driver, and a control subsystem configured to, when a magnitude of the modulated input signal falls below a threshold magnitude, control the voltage regulator to control the supply voltage such that the output signal varies non-linearly with the modulated input signal for magnitudes of the modulated input signal below the threshold magnitude.

A sound processing device includes an amplifier, a current detector, and a controller. The amplifier amplifies a sound signal to drive a loudspeaker. The current detector detects a value of an electric current flowing into the amplifier. The controller controls whether to supply power to the amplifier based on a predicted current value and the current detected by the current detector. The predicted current value is predicted in accordance with a volume setting and a level of the sound signal.

An amplifier includes a power amplifier that amplifies an input signal, a VI detection circuit that is connected to a rear stage of the power amplifier to detect power of an output signal of the power amplifier, and a controller that turns on the power amplifier when the input signal is inputted to the power amplifier, turns off the power amplifier when the input signal is not inputted to the power amplifier, and turns on the power amplifier when the VI detection circuit detects a voltage that exceeds a predetermined value when the power amplifier is in off state.

A variable-gain power amplifying technique includes generating, with a network of one or more reactive components included in an oscillator, a first oscillating signal, and outputting, via one or more taps included in the network of the reactive components, a second oscillating signal. The second oscillating signal has a magnitude that is proportional to and less than the first oscillating signal. The power amplifying technique further includes selecting one of the first and second oscillating signals to use for generating a power-amplified output signal, and amplifying the selected one of the first and second oscillating signals to generate the power-amplified output signal.

A variable-gain power amplifying technique includes generating, with a network of one or more reactive components included in an oscillator, a first oscillating signal, and outputting, via one or more taps included in the network of the reactive components, a second oscillating signal. The second oscillating signal has a magnitude that is proportional to and less than the first oscillating signal. The power amplifying technique further includes selecting one of the first and second oscillating signals to use for generating a power-amplified output signal, and amplifying the selected one of the first and second oscillating signals to generate the power-amplified output signal.

A common mode feedback (CMFB) loop for a differential amplifier sense an output common mode of a differential circuit and provides feedback to the gates of tail current transistors. Many CMFB loops cannot easily adjust the output common mode voltage and the output common mode may vary over process, voltage, and temperature. An improved CMFB circuit adds a control circuit to control backgates of tail current transistor device(s) of the differential circuit such that the output common mode voltage can be made adjustable.

A system may include a power converter having a maximum allowable input power drawn from a power source, an energy storage element coupled to an output of the power converter at a top plate of the energy storage element, wherein the energy storage element is configured to store excess energy, and control circuitry configured to, when an input power of the power converter exceeds the maximum allowable input power, cause excess energy stored in the energy storage element to be consumed by circuitry coupled to the output of the power converter, and in order to maintain positive voltage headroom for the circuitry coupled to the output of the power converter, selectively couple a bottom plate of the energy storage element to the power source such that excess energy stored by the circuitry coupled to the output of the power converter is consumed from the energy storage device when the input power of the power converter exceeds the maximum allowable input power.

One embodiment provides a vented box loudspeaker system comprising a speaker driver and a controller configured to receive a source signal for reproduction via the driver, determine a target displacement of the driver and a target sound pressure based on a first physical model of the system, and generate a control voltage based on the target displacement, the target sound pressure, and a second physical model of the system. Another embodiment provides a passive radiator loudspeaker system comprising an active speaker driver and a controller configured to receive a source signal for reproduction via the driver, determine a target displacement of a component based on a first physical model of the system, and generate a control voltage based on the target displacement and a second physical model of the system. In both embodiments, an actual displacement of the driver during the reproduction is controlled based on the generated control voltage.

This control device for controlling a loudspeaker (14) in a loudspeaker enclosure, comprises: an input for an audio signal to be reproduced; a supply output for supplying an excitation signal for the loudspeaker; the calculation means (26, 36, 38, 70, 71, 80, 90) for calculating, at each time instant (t), at least one predicted current (i.sub.ref(t)) for the excitation signal for the loudspeaker (14) as a function of the audio signal. It comprises an attenuator (71) that is capable of limiting the predicted current to a limited current value that is lower than a ceiling value by application, to the predicted current, of an attenuation gain which is a function of the predicted current.