Abstract: A self-oscillating amplifier system is disclosed. The system comprises a pulse modulator, a switching power amplification stage and a demodulation filter. Moreover, the system comprises a compensator including a forward filter which is a high order filter including a second order pole pair and a second order zero pair. Hereby it is possible to decrease the phase turn at low frequencies for better stability and increasing the gain of the control loop within the desired bandwidth.

Abstract: The invention relates to a compensator device for compensating signal dependent delay variations, including dead time and reverse recovery time, causing un-linearity in a Class-D amplifier where the compensator device comprises: a first input terminal for receiving an input pulse width modulated input PWM signal comprising pulses with falling flanks corresponding to a falling level transition and rising flanks corresponding to a rising level transition; and a second input terminal configured to receive the signal provided at an output switching node of a Class-D amplifier; an output terminal for providing a compensated output signal; and controllable delay means configured to receive and delay the pulse modulated input signal, thereby providing a delayed version of the input signal to said output terminal of the compensator device.

Abstract: A switching power conversion system and a method for start-up pop minimization in an audio amplifier assembly are disclosed. The switching power conversion system comprises a forward path including a compensator, a switching power stage and a demodulation filter. The system further comprises a DC-servo and a pre-charging circuit and a sequence control unit configured for providing a start-up sequence where the compensator and DC-servo are correctly biased and a bootstrap capacitor within the switching power stage is charged before the switching power stage is started. Hereby, it is e.g. possible to minimize the audible start-up pop in audio amplifier assemblies.

Abstract: A close-down pop reduction system and a method for close-down pop reduction in an audio amplifier assembly are disclosed. The switching power conversion system comprises a forward path having a compensator and a switching power stage and a signal path from an output of a comparator in the switching power stage to a sequence control unit. The signal path includes a close-down timing circuit configured to provide a timing signal. The sequence control unit is configured to eliminate the input signal, increase the switch frequency of the close-down pop reduction system and disable the switching power stage at a moment in time within a PWM pulse of the switching power stage. Hereby, it is e.g. possible to minimize the audible pop during close-down of audio amplifier assemblies.

Abstract: The invention relates to a compensator device for compensating signal dependent delay variations, including dead time and reverse recovery time, causing un-linearity in a Class-D amplifier where the compensator device comprises: a first input terminal for receiving an input pulse width modulated input PWM signal comprising pulses with falling flanks corresponding to a falling level transition and rising flanks corresponding to a rising level transition; and a second input terminal configured to receive the signal provided at an output switching node of a Class-D amplifier; an output terminal for providing a compensated output signal; and controllable delay means configured to receive and delay the pulse modulated input signal, thereby providing a delayed version of the input signal to said output terminal of the compensator device.

Abstract: A self-oscillating amplifier system is disclosed. The system comprises a pulse modulator, a switching power amplification stage and a demodulation filter. Moreover, the system comprises a compensator including a forward filter which is a high order filter including a second order pole pair and a second order zero pair. Hereby it is possible to decrease the phase turn at low frequencies for better stability and increasing the gain of the control loop within the desired bandwidth.

Abstract: A close-down pop reduction system and a method for close-down pop reduction in an audio amplifier assembly are disclosed. The switching power conversion system comprises a forward path having a compensator and a switching power stage and a signal path from an output of a comparator in the switching power stage to a sequence control unit. The signal path includes a close-down timing circuit configured to provide a timing signal. The sequence control unit is configured to eliminate the input signal, increase the switch frequency of the close-down pop reduction system and disable the switching power stage at a moment in time within a PWM pulse of the switching power stage. Hereby, it is e.g. possible to minimize the audible pop during close-down of audio amplifier assemblies.

Abstract: The invention relates to a pop reduction system for a switching power conversion system (0, 1), which system comprises an analogue control system (0) and a switching power stage (1), where the pop reduction system comprises an extra power stage (2), controllable means (3) for establishing or eliminating an extra signal path from the output of said control system (0) via said extra power stage (2) to the output terminal of said switching power conversion system (0, 1} and control means (34) for controlling said controllable means (3), whereby establishing or elimination of said extra signal path is attained. The invention furthermore relates to a corresponding method for pop reduction and generally to amplifier systems comprising the pop reduction system according to the invention.

Abstract: The invention relates to a pop reduction system for a switching power conversion system (0, 1), which system comprises an analogue control system (0) and a switching power stage (1), where the pop reduction system comprises an extra power stage (2), controllable means (3) for establishing or eliminating an extra signal path from the output of said control system (0) via said extra power stage (2) to the output terminal of said switching power conversion system (0, 1} and control means (34) for controlling said controllable means (3), whereby establishing or elimination of said extra signal path is attained.

Abstract: This invention relates to an attenuation control system (9) in a switching power conversion system comprising a digital modulator (4), for generating a modulated control signal from a (digital) source signal and a switching power state (6), said attenuation control system comprising: means for digitally attenuating the modulated signal, first gain shifting means (7) for shifting a supply voltage of said power stage between a plurality of predefined voltage levels, said first gain shifting means being arranged to decrease the power stage gain when the attenuation of the modulated signal exceeds a predefined level. This invention also relates to an attenuating method in a switching power conversion system comprising a digital modulator, for generating a modulated control signal from a (digital) source signal, and a switching power stage.

Abstract: This invention relates to an attenuation control system (9) in a switching power conversion system comprising a digital modulator (4), for generating a modulated control signal from a (digital) source signal and a switching power stage (6), said attenuation control system comprising: means for digitally attenuating the modulated signal, first gain shifting means (7) for shifting a supply voltage of said power stage between a plurality of predefined voltage levels said first gain shifting means being arranged to decrease the power stage gain when the attenuation of the modulated signal exceeds a predefined level. This invention also relates to an attenuating method in a switching power conversion system comprising a digital modulator, for generating a modulated control signal from a (digital) source signal, and a switching power stage.