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[Feature] Class D power amplifiers are rapidly becoming the technology of choice for audio products. Integration of these amplifiers in CMOS (complementary metal oxide semiconductor) designs for portable devices requires careful treatment if audio power output is to be maximized for minimal power consumption, while at the same time ensuring low electromagnetic interference and protection of loudspeakers. Papers from the 37th International Conference dealing with these themes are summarized, showing that effective solutions can be developed.

Author: Rumsey, Francis
JAES Volume 57 Issue 12 pp. 1087-1093; December 2009
Publication Date: December 29, 2009

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Gary Henderson	Comment posted January 23, 2010 @ 21:45:44 UTC (Comment permalink) I was disappointed that this feature did not include any mention of performance when subject to 'hostile' system loads; in particular the saturating-reactive loads often encountered on 100 V (and 70 V) distributed speaker systems in hotels and shopping-centres. Class-D amplifiers would seem to offer considerable advantage over Class-B in such situations because operation of the output devices in the 'active' region is avoided and reactive power is readily returned ot the amplifier supply-rails. (Operation in Class-G or -H is established as offering reduced device dissipation in the same circumstances.) But I have seen no discussion of possible snags; nor has there been anything said about ways of achieving 100 V output other than via a conventional audio transformer. (Respond to this comment)
Author Response Francis Rumsey	Comment posted January 25, 2010 @ 16:40:33 UTC (Comment permalink) The article was based on key topics in selected papers from the 37th conference. If those papers didn't mention the issues noted, then neither did I. I tend not to intervene, except to select material that brings out interesting themes from the published works in question. I wonder if the author of the comment might like to write a paper or an engineering report for the Journal on this topic? (Respond to this comment)
Gary Henderson	Comment posted February 12, 2010 @ 17:14:29 UTC (Comment permalink) Response understood, thank you. What I was hoping to see would be equivalent to the treatment of Class-B/Class-G issues in the fine paper by Eric Benjamin "Audio power Amplifiers for Loudspeaker Loads" (JAES Vol 42 Issue 9 Sept 1994 pp 670-683). From a series of measurement made late-2009, I was encouraged that the power consumed from the supply-rails dropped ot low levels with near-pure reactive loading. I am at the very beginnibg of the learning-curve with this type of power-amplifier so it will be some time before I could realistically take up your challenge! :-) (Respond to this comment)

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