On Mon, 17 Aug 2015 15:16:05 +0200
Attila Kinali <[email protected]> wrote:
> I have been pondering how to build a high resolution DAC over the weekend.
> Something like [1] but has the disadvantage of needing a pair of resistors
> that have a 1:2^16 ratio. The 1M/15.4R is kind of unwieldy.
> Fidling around a bit, I came to the conclusion that using an R-100R ladder
> with 4 10bit PWM DACs would be a good solution. 100R and 10k resistors
> are readily available in 0.1% 25ppm/°C (and actually quite cheap).
> While the first stage gives 10bits, each additional stage gives
> approximately another 7bits, resulting in a total of 29bits resolution.
> The 3 remaining bits per stage can be used to linearize the whole
> circuit.
Maybe a small clarification here:
The goal is to build a DAC with 26bit resolution and small DNL.
INL is not the critical value, but the output should be kind of stable.
But given how reality looks like, i would already be happy with 24bit and
would accept something >20bits as well. (For 20bit there are decent
chips at cheap prices available)
Attila Kinali
--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neil Stephenson
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