High Performance Digital Feedback for PWM Digital Audio Amplifiers
Non-idealities associated with the power stage of pulse width modulated (PWM) based, open loop digital audio amplifiers limit their performance. A high performance digital feedback system corrects for both power supply noise and power stage non-linearity in a PWM digital audio amplifier. An integrated circuit (IC) implementation of this system, along with measured results, is presented. The PWM amplifier, switching between 300 kHz and 400 kHz, achieves an unweighted dynamic range in excess of 100 dB, linearity in excess of 80 dB, and excellent power supply rejection (PSR) with a large scale audio signal.
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