All Amplifiers are Analogue, but Some Amplifiers are More Analogue than Others
This paper intends to clarify the terms "digital" and "analogue" as applied to class-D audio power amplifiers. Since loudspeaker terminals require an analogue voltage, an audio power amplifier must have an analogue output. If its input is digital, digital-to-analogue conversion is executed at some point. Once a designer acknowledges the analogue output properties of a class-D power stage, amplifier quality can improve. The incorrect assumption that some amplifiers are supposedly digital, causes many designers to come up with twisted digital patches to ordinary analogue phenomena such as timing distortion or supply rejection. This irrational approach blocks the way to a rich world of well-established analogue techniques to avoid many of these problems and realize otherwise unattainable characteristics such as excellent THD+N and extremely low output impedance throughout the audio band.
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