2023 question paper

DIGITAL ELECTRONICS

17 questions

  1. Q1a. Convert the decimal number 108.25 to its binary equivalent.20232m

    Module 1: Fundamentals and Logic Families

    Convert the decimal number 108.25 to its binary equivalent.

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    Worked Solution

    Answer

    Decimal 108.2510=1101100.012108.25_{10} = \mathbf{1101100.01_2}

    Explanation

    We convert integer and fractional parts separately.

    1. Integer part: 10810108_{10} → binary

    Use repeated division by 2:

    Division Quotient Remainder
    108 ÷ 2 54 0
    54 ÷ 2 27 0
    27 ÷ 2 13 1
    13 ÷ 2 6 1
    6 ÷ 2 3 0
    3 ÷ 2 1 1
    1 ÷ 2 0 1

    Reading remainders bottom → top:
    10810=11011002108_{10} = 1101100_2
    Verification: 1⋅64+1⋅32+0⋅16+1⋅8+1⋅4+0⋅2+0⋅1=1081\cdot64 +1\cdot32 +0\cdot16 +1\cdot8 +1\cdot4 +0\cdot2 +0\cdot1 = 108.

    2. Fractional part: 0.25100.25_{10} → binary

    Repeated multiplication by 2:

    • 0.25×2=0.500.25 \times 2 = 0.50 → 0
    • 0.50×2=1.000.50 \times 2 = 1.00 → 1 → terminate (fraction = 0)

    Reading integers top → bottom:
    0.2510=0.0120.25_{10} = 0.01_2

    3. Combine

    108.2510=1101100.012108.25_{10} = 1101100.01_2

    Check

    1101100.012=64+32+8+4+0/2+1/4=108+0.25=108.251101100.01_2 = 64+32+8+4 + 0/2 +1/4 =108 +0.25 =108.25 ✓

    Final Answer

    108.2510=1101100.012\mathbf{108.25_{10} = 1101100.01_2}

  2. Q1b. Draw the truth table of JK flip-flop.20232m

    Module 3: Sequential Circuits

    Draw the truth table of JK flip-flop.

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  3. Q1c. Draw the truth table and logic circuit of a half-adder.20232m

    Module 2: Combinational Circuits

    Draw the truth table and logic circuit of a half-adder.

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  4. Q1d. Write the difference between combinational and sequential circuits.20232m

    Module 2: Combinational Circuits

    Write the difference between combinational and sequential circuits.

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  5. Q1e. Draw the timing diagram of SR flip-flop.20232m

    Module 3: Sequential Circuits

    Draw the timing diagram of SR flip-flop.

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  6. Q1f. Find 2's complement of 1011011.20232m

    Module 1: Fundamentals and Logic Families

    Find 2's complement of 1011011.

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  7. Q1g. Number of 2:1 multiplexers required to design a 256:1 multiplexer.20232m

    Module 2: Combinational Circuits

    Number of 2:1 multiplexers required to design a 256:1 multiplexer.

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  8. Q1h. Add hexadecimal numbers 2ABC and 78F2.20232m

    Module 1: Fundamentals and Logic Families

    Add hexadecimal numbers 2ABC and 78F2.

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  9. Q1j. What is the use of a K-map?20232m

    Module 1: Fundamentals and Logic Families

    What is the use of a K-map?

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  10. Q2a. Implement the function: F(A, B, C) = \Sigma m(0,1,2,3,7)20237m

    Module 2: Combinational Circuits

    Implement the function: F(A,B,C)=Σm(0,1,2,3,7)F(A, B, C) = \Sigma m(0,1,2,3,7)

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  12. Q2b. Realize XNOR logic function using NAND gates only.20237m

    Module 1: Fundamentals and Logic Families

    Realize XNOR logic function using NAND gates only.

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  13. Q3. Simplify: Y = ABC + AB'C + A'BC202314m

    Module 2: Combinational Circuits

    Simplify: Y=ABC+AB′C+A′BCY = ABC + AB'C + A'BC

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  14. Q4. Design a logic circuit with inputs A, B, C, D and output Y, where Y = 1 when A and B are both high, and C and D are either both low or both high.202314m

    Module 2: Combinational Circuits

    Design a logic circuit with inputs A, B, C, D and output Y, where Y = 1 when A and B are both high, and C and D are either both low or both high.

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  15. Q5. Explain clocked SR flip-flop with the help of a master–slave flip-flop.202314m

    Module 3: Sequential Circuits

    Explain clocked SR flip-flop with the help of a master–slave flip-flop.

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  16. Q7. Summarize the design procedure for a synchronous sequential circuit.202314m

    Module 3: Sequential Circuits

    Summarize the design procedure for a synchronous sequential circuit.

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  17. Q8a. Explain the working of a ladder DAC with diagram.20237m

    Module 4: A/D and D/A Converters

    Explain the working of a ladder DAC with diagram.

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  18. Q8b. Design a 3-bit binary counter using T flip-flops.20237m

    Module 3: Sequential Circuits

    Design a 3-bit binary counter using T flip-flops.

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