[time-nuts] Precision DACs (was: NCOCXO anyone?)

David davidwhess at gmail.com
Sun Jul 24 20:17:29 EDT 2016

On Sat, 23 Jul 2016 20:36:28 +0200, you wrote:

>On the other hand, a modern DACs like the AD5791 reaches full 20bit at 1Msps
>(resp 1us settling time to 0.02% @10V step, or 1us to 1LSB @500 code step).
>But using the AD5791 in a design isn't easy either. The dual voltage reference
>that is required to reach full spec is kind of inconvenient. And as phk already
>wrote, these DACs deliver you the reference accuracy and noise very precisely.
>A nice write-up on issues in this area can be found at[1]
>			Attila Kinali
>[1] "The 20-Bit DAC Is the Easiest Part of a 1-ppm-Accurate Precision
>Voltage Source", by Maurice Egan, 2010

The AD5791 is pretty impressive although it comes with an equally
impressive price.  That right there looks like 10 years of improvement
given the age of the LTC2400.

I see what you mean about the positive and negative voltage reference
requirement.  Analog Devices might as well have written "magic
positive and negative reference source here" in their typical
operating circuit schematic.

There *has* to be a better way to do this.  Maybe we could build a
wooden badger ...

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