[time-nuts] DAC performance [WAS: Papers on timing for lunar laser ranging]

Charles Steinmetz csteinmetz at yandex.com
Sun Jul 16 14:24:24 EDT 2017


Bert wrote:

>  We limited to affordable  and solderable.
>  The LTC1655 was the clear winner because
>  of linearity and temperature
>       *     *     *
>  Five years later I know no better alternative

Well, to name just the first one that comes to mind, how about the 
LTC1650?  Like the 1655, it is available in SO and DIP packages.  Its 
differential nonlinearity is >2x better than the 1655, it settles 5x 
faster (4uS vs. 20uS to 1 LSB) and is nearly 100x (40dB) quieter 
(30nV/sqrtHz vs. 280).  The 1650 has substantially lower glitch energy, 
as well (1.8nV-S for the 1650, 12nV-S for the 1655).

Not all of the better specs are required for steering an oscillator at 
GPSDO rates, but others are a distinct advantage.

I have not surveyed the field to see what other "SO or easier to solder" 
DACs are available with better performance than the 1655, but I'm sure 
there are others.

This is to take nothing away from the 1655 -- I have accounted for 
thousands of them in my own designs, and think very highly of it.

Best regards,

Charles




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