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<div><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">Yes the key thing about PDM over other methods is it doesn't have to have a fundamental
fairly low sampling rate like PWM or D-S. This gives it much faster response time to requested changes. One way to think of it is that PWM and D-S have a low pass filter on their feedback loops, which D-S actually does have, whilst PWM sort of has in the
lag of changing the M-S ratio.</span></div>
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<div class="elementToProof"><span style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);" class="elementToProof">This, and the fact that you get far less energy at the sampling
rate, is why many digital microphones have moved to using PDM, and of course most new MCUs now support this mode.<br>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> mskala@northcoastsynthesis.com <mskala@northcoastsynthesis.com><br>
<b>Sent:</b> 08 December 2023 03:30<br>
<b>To:</b> Mike Bryant <mbryant@futurehorizons.com><br>
<b>Cc:</b> Danjel van Tijn / intellijel <danjel@intellijel.com>; SDIY <synth-diy@synth-diy.org><br>
<b>Subject:</b> Re: [sdiy] Generating a large number of CV outputs</font>
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<div class="PlainText">On Fri, 8 Dec 2023, Mike Bryant wrote:<br>
<br>
> I just had a read of this and generally very well put. However you seem to<br>
> miss out mentioning PDM between the sections on PWM and Delta-Sigma. This<br>
> gives faster settling time of DC voltages than PWM, as well as other<br>
> advantages when producing audio as its easier to push the noise out of<br>
> band. <br>
<br>
I'm not sure PDM is meaningfully different from delta-sigma at the level<br>
of detail I included in the posting. The things I would want to say about<br>
it would be the same things I did say about delta-sigma. Is there an<br>
important example of a PDM scheme that is not a form of PWM nor<br>
delta-sigma modulation?<br>
<br>
-- <br>
Matthew Skala<br>
North Coast Synthesis Ltd.</div>
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