1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

How to calculate this 4 bit DAC

  1. Jun 29, 2017 #1
    < Mentor Note -- thread moved to HH from the technical forums, so no Homework Help Template is shown >

    please can somebody help me, how to calculate this 4 bit dac,
    i know this one if input 1.1.1.1 5/2, 5/4 5/8 5/16 voltage

    i dont understand nothing i search on the internet but i dont find some useful example,
    my english is not so good....
    please one more time can somebody explain me how to calculate, for formula thanks
    ice_screenshot_20170630-161958.png
     
    Last edited by a moderator: Jun 29, 2017
  2. jcsd
  3. Jun 29, 2017 #2

    berkeman

    User Avatar

    Staff: Mentor

    Try again, using the search terms R-2R ladder DAC.

    After you have done that reading, try again to work your schoolwork problem and post your work here so we can check it.
     
  4. Jun 29, 2017 #3

    Merlin3189

    User Avatar
    Gold Member

    BTW, can you check your circuit, as I think the op-amp has the inputs reversed.

    Berkeman beat me to the rest of the comment.
     
  5. Jun 29, 2017 #4

    berkeman

    User Avatar

    Staff: Mentor

    Good catch!
     
  6. Jun 29, 2017 #5
    thank you a lot , it help me, thanks...
    have nice night.
     
  7. Jun 29, 2017 #6

    berkeman

    User Avatar

    Staff: Mentor

    Also, you show the output component as a Comparator. It should be a Op-Amp, not a Comparator.
     
  8. Jun 29, 2017 #7
    You really should look up another version of the R 2R ladder.
    -1 if key A is closed, the positive supply is short circuited to the output of the op-amp. That won't end well.
    2 R1 shouldn't be there.
    3 The ampiflier you connect the R-2R ladder to should have infinite (much larger than R) imput resistance.
    4 The inputs should be connected to either 0 or 5 volts, and not left unconnected.

    The last point is essential to make make the superposition principle work. If you have a network of resistors and voltage sources, you can calculate the effect of a single voltage source by replacing all the other voltage sources with a wire. You can than sum those indivudual effects to get the output voltage. Replacing the voltage sources by open circuits won't work.
     
  9. Jun 30, 2017 #8
    Good Morning

    i solve all the problme with voltage divider i find all the values.
    but the problem is, when i push key D, the voltage of D is the same(like i find it with voltage divider), but the voltage on c,b,a they have other value?
    how do i calculate ?because i draw the circuit in gsm (every circuit)
    thanks...
     
  10. Jun 30, 2017 #9

    Baluncore

    User Avatar
    Science Advisor

    The circuit in post #1 is a weird mix of several ideas.
    Please post your revised circuit diagram.
     

    Attached Files:

    Last edited: Jun 30, 2017
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: How to calculate this 4 bit DAC
  1. Designing a 4 bit ALU (Replies: 9)

Loading...