Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

ADC converter question about the LSB

  1. Jan 25, 2012 #1
    1. The problem statement, all variables and given/known data
    Show that the least significant bit (LSB) corresponds to a change in the analog signal of V/(2^N-1).

    2. Relevant equations
    D=b_0 * 2^0 +b_1 * 2^1 + ... + b_(N-1) * 2^(N-1), where b_0 is the LSB, and b_(N-1) is the MSB.

    3. The attempt at a solution
    I have absolutely have no idea what they are asking or how to solve it. I tried using the fact that 0 means logic 0 (off) and V means logic 1 (on). I think that the change in analog signal that they are talking about means that from when the bit number changes from the LSB to the next bit number, the change in amplitude of the analog signal. I tried that fact that 2^0 equals 1, and plugged that into the given expression, but that still did not make any sense. Does "correspond" mean that the LSB is proportional, or equal to the change in analog signal?
    How can I solve this problem?
  2. jcsd
  3. Jan 25, 2012 #2
    You have a 5 volt chip. The lowest value it can read is 0 volts and that's a 0 after conversion. The largest value is for 5 volts and will be read as all bits = 11111...1.

    The question is, how many volts will get converted into 000....001?
  4. Jan 27, 2012 #3
    Thank you very much! This helped a lot.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook