VERFAHREN ZUR REDUZIERUNG VON NULLDURCHGANGSVERZERRUNGEN UND RAUSCHEN IN EINEM VERSTÄRKER, VERSTÄRKER SOWIE ANWENDUNG DIESES VERFAHRENS UND VERSTÄRKERS

摘要

According to the invention, a method and an amplifier e.g. of the class D type, in particular connected as class BD, wherein an audio signal is pulse-with modulated in that two sets of switches are adapted to make and break signal paths transferring pulses representing the non-inverted or inverted part of the audio signal, comprise attenuating noise and zero crossing distortion which occur because of crosstalk between modulator and control circuit halves in the amplifier. Noise and zero crossing distortion are attenuated by delaying the pulses which represent the non-inverted part and the inverted part, respectively, of the audio signal relative to each other, when the audio signal is in the vicinity of the value 0, thereby achieving modulation of the audio signal which contains characteristics from pulse with modulation of both class AD and BD type. The advantage of this is that at low signal levels the amplifier obtains the linear properties of the class AD amplifiers at zero crossing and the low noise of the class BD amplifier. The pulse-with modulation type is here called class ABD.