Digital-Input Class-D Audio Amplifier
Not only digital-input class-D audio amplifier directly converts digital PCM-coded audio signal into power, it also exhibits superior performances with respect to traditional PWM analog class-D amplifiers. In the later, several analog techniques have to be deployed to combat the many side-effects inherent to analog blocks, resulting in complex circuitry. Digital domain provides many degrees of freedom that allow combating signal non-idealities with no or just little extra cost. As the output to the real world is analog, digital class-D amplifier requires Analog to Digital Conversion (ADC) in feedback to compensate for Jitter, signal distortions and power supply noise. With careful sigma delta modulation design and few digital techniques, the class-D loop is stabilized and achieves superior audio performances. The audio signal cascade chain is tremendously simplified resulting in significant reduction in area cost and power consumption. For applications that require analog input processing, the digital class-D still accepts analog inputs with no extra cost.
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