Realization of a digital PWM power amplifier using noise and ripple shaping

Abstract

A digital pulse width modulation technique featuring noise and ripple shaping (NRS) for audio power amplification is realized. The sampled and extrapolated power source amplitude signal is used to shape the interpolated input digital signal. This shaped signal is fed to a noise shaper to produce a reduced bit digital signal fully representing the original signal. The output power signal is not affected by the requantization error or the power source ripple. Therefore, DC power regulators can be eliminated without sacrificing the signal to noise ratio. A digital signal processor controlled full bridge power amplifier was built with close to 5 kHz bandwidth and 40 dB ripple rejection improvement at 60 Hz over conventional PWM power amplifiers.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>