Digital Electronics Questions For VLSI Interview

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Digital Electronics Questions For VLSI Interview

 

  1. Which gates are called universal gates? Why?
  2. Define: (a) bit (b) nibble (c) byte (d) word
  3. What is weighted code? Give example.
  4.  Give an example for Non-weighted code .
  5.  What is the key feature of Excess-3 code?
  6. What is the condition for a weighted code to be self-complementary?
  7. Convert the binary number 011101010001 to octal and hexadecimal?How many number of 2 input AND gates are required to generate N I/P AND gate?
  8. State De-Morgan’s Laws?
  9. If it is given that A & B will not be 1 at the same time, what will be theequivalent logical gate for an XOR gate?
  10.  If any of the inputs of an XOR gate are inverted, XOR gate will work as ----- ?
  11. Give implementation of XOR using minimum number of NAND gates?
  12. Which logical gates can be used as parity generators?
  13. Which logical gate can be used to find out whether the two single bit inputs are equal or not? 
  14. What is the difference between NAND gate and negative AND gate?
  15. XOR gate can be used as even parity generator and XNOR can be used as odd parity generator. 
  16.  Show the AOI implementation of a 2:1 Mux?
  17.  Convert this to 2-input NAND implementation?
  18. Design the following gates using minimum number of 2:1 Muxes    (a) NOT (b) AND (c) OR (d) XOR
  19.  Construct a 16:1 Mux with two 8:1 Mux and one 2:1 Mux.
  20. Design "OR" gate using HA's?
  21. Design a full adder using half-adders and minimum number of external gates?
  22. Give the truth table for (a) half-adder and (b) half-subtractor? 
  23. Implement a full adder using two 4:1 Muxes? 
  24.  Implement a circuit for adding two 4-bit numbers using (a) Ripple carry adder (b) Carry Look Ahead (CLA) adder 
  25. Design a subtractor unit using a 4-bit comparator, 4-bit binary adder and someexternal gates, which performs A-B if A>B and else B-A. A and B are two 4-bit binary numbers. 
  26. Give the circuit that adds two BCD numbers and gives out a BCD number? 
  27. How will you count the number of 1's that are present in a given 3-bit input using full adder? 
  28. Mention two basic applications of flip-flops?
  29.  What is the difference between a LATCH and a Flip flop?
  30. What is transparent latch?
  31.  Implement S-R Latch with control input using 2-input NAND gates?
  32.  Which input combinations are not allowed in (a) NAND based (b) NOR based S-R Latch? Explain.
  33.  How to convert S-R Latch to transparent latch?
  34. Design a D-latch using 2:1 Mux.
  35. Design a master-slave D-Flip flop using D-Latch?
  36.  What is race-around condition? Explain it in case of J-K Latch and solution to avoid that? 
  37. Implement T-flip flop from D-flip flop?
  38.  Show how to convert J-K flip flop into (a) T-flip flop (b) D-flip flop?
  39.  What is excitation table?
  40.  Write the excitation table for T-flip flop?
  41.  Draw the circuit for a D flip flop with Synchronous Reset? 
  42. Give the characteristic table and characteristic equation for J-K Flip-flop?
  43. Construct a J-K flip flop using a DFF, 2:1 Mux and an-inverter?
  44. What are stuck-at problems? Explain the reason for their occurrence? 
  45. What do you mean by CMOS technology? Explain with a block diagram.
  46.  What are the advantages and disadvantages of CMOS logic? 
  47.  Show the circuit for CMOS inverter and explain the basic operation?
  48.  Draw the VTC of a CMOS inverter?
  49. Draw the CMOS implementation of NAND and NOR gates
  50. Using open-collector NAND gate, implement Y = (AB + CD)’ ? 
  51. What is Latch Up? How do you avoid Latch Up? 
  52. Latch and Flipflop  Difference ?





    


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