[sdiy] Generating a large number of CV outputs

[David Kantowitz]

A few sentences here about how FPGA is used to generate DAC outputs from
FPGA for 3 Body oscillator.
https://youtu.be/iVmGgd6gzJ0?t=192




On Thu, Dec 7, 2023 at 6:01 PM Mike Bryant <mbryant at futurehorizons.com>
wrote:

>
>    - https://northcoastsynthesis.com/news/dacs-and-bit-count/
>    et seq
>
>
> I just had a read of this and generally very well put.  However you seem
> to miss out mentioning PDM  between the sections on PWM and Delta-Sigma.
> This gives faster settling time of DC voltages than PWM, as well as other
> advantages when producing audio as its easier to push the noise out of
> band.
>
> I used PDM (using 74LS TTL and some transistors) in the 1980s for an
> accurate fast settling DC voltage reference in a HP instrument requiring
> better then 16 bits as one of its uses was to verify in production the then
> new 16 bit(-ish) convertors.
>
> ------------------------------
> *From:* Synth-diy <synth-diy-bounces at synth-diy.org> on behalf of Matthew
> Skala via Synth-diy <synth-diy at synth-diy.org>
> *Sent:* 08 December 2023 01:21
> *To:* Danjel van Tijn / intellijel <danjel at intellijel.com>
> *Cc:* SDIY <synth-diy at synth-diy.org>
> *Subject:* Re: [sdiy] Generating a large number of CV outputs
>
> On Thu, 7 Dec 2023, Danjel van Tijn / intellijel wrote:
>
> > Let's say I wanted to generate 100 outputs with an update rate of a few
> kHz
> > and an equivalent bit depth of 12 or 16 bits.
>
> Which is it, 12 or 16?  You've got your work cut out for you if you really
> want 16-bit absolute DC voltage precision on even one output.  The number
> of outputs isn't your biggest concern when that's a serious goal.
>
> > Now that DACs are cheaper, is it better to chain a bunch of 8- or
> 16-channel
> > DACs?
> >
> > Or would it make more sense to use an FPGA and create a giant
> multi-channel
> > 1-Bit DAC?
>
> Using an FPGA is going to require you to solve for yourself a lot of
> problems that would be solved for you if you used ready-made DAC chips.
> I wouldn't be eager to do that.  I also don't think 1-bit DACs are
> well-suited to generating precise DC voltages; as I wrote at length in my
> recent Web log series (
> https://northcoastsynthesis.com/news/dacs-and-bit-count/
> et seq.), they reproduce signals, not voltages.
>
> However, if you do put in the effort to make it work, the FPGA would
> probably be cheaper.
>
> --
> Matthew Skala
> North Coast Synthesis Ltd.
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