ASIC Logic Interview Questions Part # 3

1) Create "AND" Gate using a 2:1 multiplexer. ( Create all other gates too)


Answer:



   Z = XS + Y/S


  If  X=0, Y=1,
    Z =  /S    ( Inverter gate)

  If X=1, Y=0,
   Z = XS   ( AND gate )

   With AND gate and inverter, it's a basic building gate NAND.



2) What is the minimum logic gates required to generate any boolean function?

Answer:




NAND and NOR are the universal gates. They can created any gates as following:


Use NAND to create an inverter




Use NAND to create a NOR gate



Use NAND to create a XOR gate



XNOR can be created with additional inverter.