Testing DAC

Discussion in 'The Projects Forum' started by shantanu, Dec 17, 2008.

  1. shantanu

    Thread Starter Member

    May 26, 2008
    25
    0
    Hi,

    I am working on a current steering DAC circuit. I am done with schematics and layout portion of the project. Now I have to characterize its performance. I want to know the way to test it for INL and DNL through simulation. I already tested for its functionality with an Ideal ADC. I also need to know how do I test for its settling time through simulation.

    I am using free tool LTSpice for all my simulations. Please, if any one can throw some light on testing techniques , it will be helpful.

    regards
    SG
     
  2. Ron H

    AAC Fanatic!

    Apr 14, 2005
    7,050
    656
    Why don't you just make a model of an ideal DAC and subtract its output from your DAC's output?
     
  3. shantanu

    Thread Starter Member

    May 26, 2008
    25
    0
    thanks, but I was looking for some information on testing a real DAC chip.
     
  4. Ron H

    AAC Fanatic!

    Apr 14, 2005
    7,050
    656
    That's not what you said.
    Many years ago I tested a DAC by driving it with a binary counter, generating a very linear ramp with a current source and capacitor, or an integrator, and then subtracting the ramp from the DAC output.
    Generating a linear ramp is not a trivial task. You must pay attention to things like capacitor dielectric absorption, current source impedance, etc.
     
  5. shantanu

    Thread Starter Member

    May 26, 2008
    25
    0
  6. John Luciani

    Active Member

    Apr 3, 2007
    477
    0
    To test for INL and DNL I would do the following ---

    1. Measure the -FS voltage, mid-point voltage and the +FS voltage
    and calculate INL

    2. For DNL I would calculate the LSB size at all of the major carries.
    For example an 8-bit DAC would have 8 major carries ---

    0000 0000 to 0000 0001,
    0000 0001 to 0000 0010,
    0000 0011 to 0000 0100
    .
    .
    0111 1111 to 1000 0000

    (* jcl *)
     
Loading...