[volt-nuts] Building a high resolution DAC

Azelio Boriani azelio.boriani at gmail.com
Mon Aug 17 09:28:10 EDT 2015


Best to ask volt-nuts?

On Mon, Aug 17, 2015 at 3:16 PM, Attila Kinali <attila at kinali.ch> wrote:
> Hi,
>
> 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.
>
> Now this is where the problem starts. How do I measure the circuitry
> to build a linearization table? The linearity error is dominated by
> the first stage error which is in the order of 0.1% and thus 10bits.
> It would be necessary to measure this to somewhere close to 29bits, but
> the best DACs that are readily available are 24bit. Yes, there is the
> possibility to build some ADC that could do 28bit, but I am not exactly
> keen on building something aking an HP3458 (mostly to avoid the
> embarrasment of failing at doing so).
>
> So, the question is how would one calibrate something like this?
> Or am I missing something fundamental here?
>
>
> Thanks in advance
>
>                         Attila Kinali
>
> [1] "DC-accurate 32-bit DAC achieves 32-bit resolution",
> by Stephen Woodward, 2008
>
> --
> 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
> _______________________________________________
> volt-nuts mailing list -- volt-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> and follow the instructions there.


More information about the volt-nuts mailing list