A loudspeaker real-time state variable prediction system may include a loudspeaker having a voice coil and a magnet, and a non-linear excursion model configured to estimate non-linear excursion of the loudspeaker. The system may further include a thermal model configured to utilize thermal parameters and frequency based on at least one thermal property of the loudspeaker, and a gain adjustment thermal limiter configured to apply a gain reduction an incoming audio signal to protect the loudspeaker from thermal overload.

An automatic gain control apparatus includes an amplitude detecting circuit, a distortion detecting circuit, a gain determining circuit and an amplifying circuit. The amplifying circuit applies a gain to an input signal to generate an output signal. The amplitude detecting circuit detects an average amplitude of the input signal. The distortion detecting circuit detects a distortion level of the output signal. The gain determining circuit determines the gain used by the amplifying circuit according to the average amplitude and the distortion level.

An automatic gain control apparatus includes an amplitude detecting circuit, a distortion detecting circuit, a gain determining circuit and an amplifying circuit. The amplifying circuit applies a gain to an input signal to generate an output signal. The amplitude detecting circuit detects an average amplitude of the input signal. The distortion detecting circuit detects a distortion level of the output signal. The gain determining circuit determines the gain used by the amplifying circuit according to the average amplitude and the distortion level.

A sensor circuit is provided with a chopper-stabilized amplifier circuit configured to receive a signal from at least one magnetic sensing element, a sigma-delta modulator (SDM) configured to receive a signal from the chopper-stabilized amplifier circuit, and a feedback circuit configured to reduce ripple in a signal generated by the chopper-stabilized amplifier circuit. The feedback circuit includes a demodulator to demodulate a signal from the SDM in a digital domain by inverting a bit stream of the signal from the SDM according to a frequency chopping rate, a digital integrator configured to integrate an output signal of the demodulator to form an integrated signal, and a digital-to-analog converter (DAC) configured to convert the integrated signal to an analog signal and provide the analog signal to the chopper-stabilized amplifier circuit.

A sensor circuit is provided with a chopper-stabilized amplifier circuit configured to receive a signal from at least one magnetic sensing element, a sigma-delta modulator (SDM) configured to receive a signal from the chopper-stabilized amplifier circuit, and a feedback circuit configured to reduce ripple in a signal generated by the chopper-stabilized amplifier circuit. The feedback circuit includes a demodulator to demodulate a signal from the SDM in a digital domain by inverting a bit stream of the signal from the SDM according to a frequency chopping rate, a digital integrator configured to integrate an output signal of the demodulator to form an integrated signal, and a digital-to-analog converter (DAC) configured to convert the integrated signal to an analog signal and provide the analog signal to the chopper-stabilized amplifier circuit.

Audio distortion by a speaker may be reduced by detecting onset audio events within an audio signal and modifying the audio to reduce the audio distortion perceived by a listener. The onsets may be detected using a psych-acoustic model by determining critical sub-band powers and corresponding masking thresholds. When a loudness value calculated from the CSBs and masking thresholds exceeds a threshold level, certain frequency bands may be attenuated and other frequency bands may be amplified. The audio modification may be performed on a frame-by-frame basis and each frame may be processed multiple times until the onset is sufficiently masked or attenuated.

Audio distortion by a speaker may be reduced by detecting onset audio events within an audio signal and modifying the audio to reduce the audio distortion perceived by a listener. The onsets may be detected using a psych-acoustic model by determining critical sub-band powers and corresponding masking thresholds. When a loudness value calculated from the CSBs and masking thresholds exceeds a threshold level, certain frequency bands may be attenuated and other frequency bands may be amplified. The audio modification may be performed on a frame-by-frame basis and each frame may be processed multiple times until the onset is sufficiently masked or attenuated.

An amplifier apparatus is arranged to amplify an input signal with a gain based on a digital gain control signal. The amplifier apparatus comprises a digital-to-analogue converter arranged to convert the digital gain control signal into an analogue gain control signal according to a first non-linear relationship between digital gain control signal and analogue gain control signal; and an amplifier circuit portion arranged to amplify the input signal with a gain based on the analogue gain control signal according to a second non-linear relationship between analogue gain control signal and gain. The first non-linear relationship is based on the second non-linear relationship.

A method and electronic circuit for changing the gain of a radio frequency signal. The apparatus is an electronic circuit comprising one or more variable gain electronic elements, and one or more adjustable phase shifting elements. The method comprises the steps of receiving a radio frequency signal, varying the gain of the variable gain electronic element while the variable gain electronic element changes the amplitude of the radio frequency signal, and adjusting an adjustable phase shifting element to generate a reverse phase shift in the radio frequency signal in response to the associated phase shift from the step of varying the gain.

A method and electronic circuit for changing the gain of a radio frequency signal. The apparatus is an electronic circuit comprising one or more variable gain electronic elements, and one or more adjustable phase shifting elements. The method comprises the steps of receiving a radio frequency signal, varying the gain of the variable gain electronic element while the variable gain electronic element changes the amplitude of the radio frequency signal, and adjusting an adjustable phase shifting element to generate a reverse phase shift in the radio frequency signal in response to the associated phase shift from the step of varying the gain.