[sdiy] CMOS Switch as VCA?

[Scott Nordlund]

The 4016 isn't buffered though, that's primarily the one I was thinking about.  The only thing I had in my mind about the 4066 was its lower on resistance, but yeah, it is buffered so never mind.  The 4016 does have an inverter to drive the P-MOSFET so I would expect some nonlinearity due to that.  I'm not hoping for anything approaching hi-fi, but I think the idea would be useful in some way even if it only barely works.

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> Date: Mon, 8 Feb 2010 13:53:11 -0800
> From: dlmanley at sonic.net
> CC: synth-diy at dropmix.xs4all.nl
> Subject: Re: [sdiy] CMOS Switch as VCA?
>
>
>>>> Forgive the dumbness of the question, but has anyone tried using a standard CMOS switch (4016/4066) as a "sort of" VCA? I mean with an actual linear CV input, not using PWM. I haven't tried it and I've never seen any reference to it, but I can picture it almost working, though probably not in an optimal kind of way. At least it wouldn't have the CV feedthrough problems of a single transistor VCA....
>>>>
>>>> Any ideas?
>>>>
>>>>
> Per the datasheet the 4066 control inputs are buffered through 3
> inverters. You won't get any kind of linear response using this part.
> Most of the "oddball" CD4xxx circuits that use "digital" parts for
> analog purposes use the "UB", or "unbuffered" parts which allows them to
> be used, pretty much, as a bunch of transistors in one package. Google
> "cd4069 linear" for some relevant info.
>
> -Dave
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