Digital Electronics Combinational Logic Circuits Questions and Answers
The Combinational Logic Circuits questions with answers focus on logic gates, Boolean algebra, K-maps, and circuit simplification techniques in digital electronics. These logical reasoning questions and answers help students understand how digital systems process information. Frequently asked in ECE exams and electronics company placements like BEL, ISRO, and TCS, these questions strengthen analytical and circuit design skills. Study the truth tables, logic expressions, and practical implementations to master this essential topic in digital design.
Digital Electronics Combinational Logic Circuits
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59 questions
21. Which of the following expressions is in the sum-of-products form?
- (A + B)(C + D)
- (AB)(CD)
- AB(CD)
- AB + CD
22. A decoder can be used as a demultiplexer by ________.
- tying all enable pins LOW
- tying all data-select lines LOW
- tying all data-select lines HIGH
- using the input lines for data selection and an enable line for data input
23. How many 4-bit parallel adders would be required to add two binary numbers each representing decimal numbers up through 30010?
- 1
- 2
- 3
- 4
24. Which statement below best describes a Karnaugh map?
- A Karnaugh map can be used to replace Boolean rules.
- The Karnaugh map eliminates the need for using NAND and NOR gates.
- Variable complements can be eliminated by using Karnaugh maps.
- Karnaugh maps provide a visual approach to simplifying Boolean expressions.
25. A certain BCD-to-decimal decoder has active-HIGH inputs and active-LOW outputs. Which output goes LOW when the inputs are 1001?
- 0
- 3
- 9
- None. All outputs are HIGH.
26. The design concept of using building blocks of circuits in a PLD program is called a(n):
- hierarchical design.
- architectural design.
- digital design.
- verilog.
27. When adding an even parity bit to the code 110010, the result is ________.
- 1110010
- 1111001
- 110010
- 001101
28. Which of the following combinations of logic gates can decode binary 1101?
- One 4-input AND gate
- One 4-input AND gate, one OR gate
- One 4-input NAND gate, one inverter
- One 4-input AND gate, one inverter
29. What is the indication of a short to ground in the output of a driving gate?
- Only the output of the defective gate is affected.
- There is a signal loss to all load gates.
- The node may be stuck in either the HIGH or the LOW state.
- The affected node will be stuck in the HIGH state.
30. How many outputs would two 8-line-to-3-line encoders, expanded to a 16-line-to-4-line encoder, have?
- 3
- 4
- 5
- 6