Re: [Discuss-gnuradio] speed difference between ADCs and DAC's

[Ebtisam Ahmed]

Hi all,

Well going into the basics, ADCs have a sample and hold circuits. It
holds the value and sometimes takes the average of some nearby values
and then convert that into digital for precision. While there is no
such thing in DACs; resulting in faster DACs.

Hope this helps..

Regards,
Ebtisam

On Sun, May 27, 2012 at 7:23 AM, wayne roberts <address@hidden> wrote:
> I dont know if that tutorial covers the topic, try this
> http://www.analog.com/library/analogDialogue/archives/39-06/Chapter%202%20Sampled%20Data%20Systems%20F.pdf
>
> I think its simple to say why DAC and ADC operate a different speeds.
> Its not just speed, also dynamic range (ENOB) is also more difficult to
> achieve in ADC.
> Ultimately an ADC must guess at what the analog input is due to internal
> noises (sample and hold hi-z, etc), which is why the ENOB is always worse
> than the number of bits output digitally.
>
> By contrast, the DAC since it operates in reverse, it already knows exactly
> what the signal should be, and just needs to switch in the correct resistor
> to produce the correct analog value.
>
> A high speed ADC/DAC expert would say this is an over-simplification, but I
> only try to convey the basic idea.
>
> On Wed, May 23, 2012 at 2:41 AM, Sravya Reddy <address@hidden>
> wrote:
>>
>> hi everyone,
>>
>> USRP board has ADC's and DAC's operating with different speeds. why DAC's
>> are faster than ADC's? please excuse me if it is a basic question.
>>
>> thanks in advance,
>> sravya.
>>
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