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Homework Help: Implement XNOR using NAND gates ?

  1. May 26, 2009 #1
    what is minimum number of NAND gates to implement XOR?
    i thought it in this way .first i found how many NAND gates are need to to implement XOR .
    if the two input it 'A' nd 'B'
    XOR function =A'B+AB'
    so i need two NAND gates to invert A and B
    then for two AND gates i need another 4 NAND gates as each AND gate need 2 NAND gates .
    then for final OR gate i need another 3 NAND gate .
    so this will give the XOR function .To make it XNOR i need another NAND gate

    so total number of NAND gates=2+4+3+1=10

    but in my MCQ question it has only
    a)3 b)4 c)5 d)6

    i dont how to implement XNOR in one of above answers ,totally by NAND gates .can somebody help me ?
    Thanks !!!!!!!!!
  2. jcsd
  3. May 26, 2009 #2
    Three NAND gates can be combined to produce the double AND plus OR function. The rest are just those required for the invert operations.
  4. May 26, 2009 #3
    ok thnaks !!!!!!!!and i found some good ideas from wikepedia also !!!!!!!
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