ADC applications

Discussion in 'Homework Help' started by IronGhost, Apr 4, 2007.

  1. IronGhost

    Thread Starter New Member

    Apr 4, 2007
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    From my understanding there are Flash ADC's, successive approximation, and sigma-delta. My question is where are these three different ADC's used? What are their real world applications? Any help would be greatly appreciated.
     
  2. John Luciani

    Active Member

    Apr 3, 2007
    477
    0
    In general --- flash is the fastest, multiple comparators, one cycle
    successive approximation is slower (multiple comparasons) and sigma delta
    is slowest but achieves high accuracy at low cost.

    Typical applications ---

    Flash would be used for video and metrology, SA for various data aquisition and metrology systems and SD for slow data aquisition systems and audio systems.

    For detailed information ---

    http://www.analog.com/library/analogDialogue/archives/39-06/data_conversion_handbook.html

    (* jcl *)

    ----
    www.luciani.org
     
  3. Dave

    Retired Moderator

    Nov 17, 2003
    6,960
    144
    You will find sigma-delta is the defacto for high-fidelity digital audio processing applications because of its high resolution and speed; as an example I regularly use the CS4271, a 24-bit, dual channel sigma-delta based codec which can sample up to 200kHz.

    The advantages afforded by sigma-delta ADCs are that the integrator circuit at the ADC input acts as a sample and hold therefore no additional circuitry required, the operation is frequency dependant thereforeits output drops to zero at the Nyquist point therefore no anti-aliasing circuitry is required, and the quantiser rate is high (if the ADC generates data words at f Hz, then the sigma-delta quantiser samples at ~128f Hz) then the noise power is spread over a wide frequency bandwidth. Finally, it is very simple to recover the sampled analogue signal by integrating the bipolar signal at the output of the DAC.

    Applications for Flash ADCs are generally those that require the speed at the expense of cost; a few that spring to mind include frame-stores for video signals, transient recorders and radar signal processors.

    I also recommend a look at Volume 4 - Chapter 13.

    Dave
     
  4. IronGhost

    Thread Starter New Member

    Apr 4, 2007
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    Thanks for all the help. I really appreciate it guys. In case you guys were wondering I ask this because I'm in a design class (Cal Poly SLO), and we are designing a satellite system around the moon to give 24/7 communication (video quality). One of my jobs right now is to figure out what kind of ADC we're going to use on the satellites.

    Again, thanks for the help guys.
     
  5. Dave

    Retired Moderator

    Nov 17, 2003
    6,960
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    Well then look at the commercial sigma-delta codec units giving you both ADC and DAC capabilities, I have given one such example that I use above, but you could look at others from the same manufaturer, Cirrus Inc.

    Dave
     
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