[sdiy] Using DG-series analog switches for PWM VCA

rsdio at audiobanshee.com rsdio at audiobanshee.com
Thu Jun 14 07:52:51 CEST 2018

On Jun 13, 2018, at 5:52 AM, Tom Wiltshire <tom at electricdruid.net> wrote:
> Yes, “several values of ‘better’” sums it up pretty well. I’ve already got a uP in the design, so producing the PWM control signals no big deal - what R.G.Keen ironically calls “a simple matter of programming”. And the filtering isn’t going to add much either, since there would already be an op-amp buffer on both ends, and those can easily be modified into filters instead. So I think I shall try it.

Careful, with a single op-amp, you’re not going to do better than first or second order low-pass, which is a far cry from the brick wall filter needed for typical sampling. On the other hand, if your PWM is up in the MegaHertz then maybe a gentle slope will still provide enough attenuation at the resulting Nyquist.


p.s. Does anybody know why my Mac keeps “correcting” the spelling of Nyquist to Nyqvist?

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