[time-nuts] DAC performance
csteinmetz at yandex.com
Mon Jul 17 19:32:31 EDT 2017
> Charles Steinmetz <csteinmetz at yandex.com> wrote:
>> how about the LTC1650?
>> * * *
>> [it] is nearly 100x (40dB) quieter (30nV/sqrtHz vs. 280) [than the 1650]
> I was about to ask the same question :-)
Note: I divided 280 by 30 and got "nearly 100x". D'Oh! Of course, it
is ~10x, or 20dB, not ~100x or 40dB as I stated. Still, a ~20dB noise
advantage is substantial.
One point I didn't mention previously -- the 1650 is only marginally
more expensive than the 1655.
> I am sure there are ways to compensate for the charge injection
> by using multiple switches, but I have not been able to come up
> with a good way. Does anyone have a good idea?
I've tried several approaches to cancel the glitch energy of analog
switches, but I never hit on anything I was really happy with -- partly
because the glitch energy is more random than you'd like and partly
because the "kludge factor" of multiple-switch solutions exceeds my
tolerance pretty quickly. Even if you accept the high kludge factor,
you find that like input bias current cancellation, glitch cancellation
is most effective (only really effective??) if it is done on-chip.
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