hui@van-bc.UUCP (Michael Hui) (01/16/90)
Over in rec.audio there has been talk of a new D/A topology using an analog filter to extract information from a pulse width modulated waveform. The PWM waveform is of course simply constructed from the digitized audio information. Since my only strong background is in circuit design, not in DSP, I am not sure what inherent advantage this scheme would have over the now used scheme of segmented D/A's. Further adding to the puzzlement is that there has been no mention of this scheme (I might have interpreted the exact workings of the scheme incorrectly) in the literature. If you look at the December 1989 IEEE Journal of Solid State Circuits, page 1517, they are still talking about the "classic" D/A architecture of ratioed current sources or multiple identical current sources. The latest post on this thread follows: Article 15293 of rec.audio: Path: van-bc!zaphod.mps.ohio-state.edu!usc!apple!agate!shelby!lindy!ucscb.UCSC.EDU!sorka From: sorka@ucscb.UCSC.EDU (Alan Waterman) Newsgroups: rec.audio Subject: Re: New 1-bit CD Machines Message-ID: <7180@lindy.Stanford.EDU> Date: 14 Jan 90 06:47:58 GMT References: <4616.25a5ac56@uwovax.uwo.ca> <18030058@hpfcdj.HP.COM> Sender: news@lindy.Stanford.EDU (News Service) Reply-To: sorka@ucscb.UCSC.EDU (Alan Waterman) Organization: UCSC Undergrads Lines: 4 From the articles I've read, it is indicated that the new 1bit cd technology reaches the theoretical limits of sound reproduction on the current CD format.
jimb@hpmcaa.mcm.hp.com (Jim Belesiu) (01/16/90)
The greatest advantage that I see is that with a 1 bit D/A the implementation can be realized with a digital IC at a lower cost than a digital-analog IC. I am not sure if one can claim that the analog filtering requirements are any less complicated for a one bit D/A as compared to a multi-bit D/A. Jim