A use of sigma-delta modulation in power digital-to-analogue conversion

Power digital-to-analogue (D–A) converters have applications in digital audio, portable equipment and industrial control systems. This paper discusses the use of sigma–delta modulation as the primary processing block in power D–A systems. The focus is on the pulse repetition frequency (PRF) of the one-bit output and its suitability for power switching. It is shown that in order to preserve high power efficiency and tolerance to a non-ideal output stage, the PRF of the output may be reduced and made constant by the use of a technique termed bit flipping. The performance of different bit flipping algorithms is discussed which aim to regulate the PRF whilst maintaining the stability of the modulation process. Results are presented which compare the performance of the different systems under the conditions of an ideal and a non-ideal output stage. © 1997 by John Wiley & Sons, Ltd.