Class D Audio Amplifier Output Filter Optimization

Abstract: This application note examines the effect of the output filter on audio Class D amplifier performance. Switch-mode amplifiers such as the MAX4295 and MAX4297 offer improved efficiency over their more traditional Class AB counterparts. By understanding the operation of these devices, the modulation noise spectrum and the loudspeaker loads they are required to drive, it is possible to completely eliminate the output filter while retaining the efficiency benefits of Class D amplifiers.
Maxim > App Notes > AMPLIFIER AND COMPARATOR CIRCUITS AUDIO CIRCUITS

Keywords: Class D, audio amplifiers, switching amplifer, output filter, modulation noise, PWM, filterless, Apr 01, 2002
amplifers

APPLICATION NOTE 624
Class D Audio Amplifier Output Filter Optimization

Abstract: This application note examines the effect of the output filter on audio Class D amplifier performance.
Switch-mode amplifiers such as the MAX4295 and MAX4297 offer improved efficiency over their more
traditional Class AB counterparts. By understanding the operation of these devices, the modulation noise
spectrum and the loudspeaker loads they are required to drive, it is possible to completely eliminate the output
filter while retaining the efficiency benefits of Class D amplifiers.


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