DAC ADC Successive Approximation

Discussion in 'Homework Help' started by Steve1992, Aug 27, 2011.

  1. Steve1992

    Thread Starter Senior Member

    Apr 7, 2006
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    In a DAC practical circuit I read the 'step' change in Vout can be given as:

    Vstep = Vref/2^n

    where n is the number of bits in the digital word.

    Eg.
    Vref = 5V
    n = 8-bits

    5V/256 = 19.5mV

    41(decimal) x 19.5mV = 800mV.



    Is it OK to use this same procedure for ADC successive approximation circuit calculations?

    Eg.
    Vsig = 3.6V
    8-bit, 5V ADC

    5V/256 = 19.5mV

    Vsig/19.5mV = 183(decimal)
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    Yes we can. The problem is: How many steps are there?
    Is it 2^n steps or 2^n -1 steps?
     
  3. Steve1992

    Thread Starter Senior Member

    Apr 7, 2006
    100
    0
    Is that a rhetorical question?

    From what Ive read its Vref/2^n

    thanks.
     
  4. Steve1992

    Thread Starter Senior Member

    Apr 7, 2006
    100
    0
    Sorry, I had got confused because I didn't know this process is known as quantization.:)
     
  5. Steve1992

    Thread Starter Senior Member

    Apr 7, 2006
    100
    0
    Sorry, I got a little lost because I didn't know this process is known as quantization.
     
  6. MrChips

    Moderator

    Oct 2, 2009
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    3,361
    Let us take a simple example.
    Suppose we have a 2-bit DAC with full-scale range of 0-3V.
    Is the step size 3/4 V or 3/3 V?
     
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