Re: Arghhh : Awefully bad noise figures in voltage DACs...

From: Joerg (notthisjoergsch_at_removethispacbell.net)
Date: 09/13/04 

Date: Mon, 13 Sep 2004 22:35:27 GMT

Hi John,

>Oh, as long as I'm raining on your parade, be aware that most serial
>DACs have nasty clock feedthrough, so expect spikes and perhaps some
>DC offset while you're clocking the data in.
>
>For lowest noise, use an external ref and a DAC that requires an
>external opamp. All you want inside the DAC is the switches and the
>thinfilm resistors.
>
>
Or use a sample and hold. SD5400 are really nice for that purpose. The
S/H needs good RF isolation else the spikes barrel right through. No
autorouter here.

Regards, Joerg

http://www.analogconsultants.com

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