New high accuracy pulse width modulation based digital-to-analogue convertor/power amplifier

Abstract

A new high accuracy pulse width modulation based digital-to-analogue convertor is presented. It is suitable for high power applications as well as ordinary low power use. While possessing important advantages, previously proposed convertors of this type have been difficult to realise in hardware and/or have exhibited high distortion. In this paper, digital signal processing (DSP) techniques are used to facilitate hardware implementation and increase performance. Specially designed oversampled noise shaping networks allow reductions in internal modulator clock speed large enough to make a 16 bit quality implementation possible. Also, new premodulation, predistortion DSP algorithms of varying complexity and accuracy are employed to reduce the harmonic distortion inherent to the modulation process typically used. Computer simulations are presented to verify the improvements.