# Interview Questions on Digital Electronics (Combinational and Sequential Circuits)

Jul 7, 2020

### Interview Questions on Digital Electronics:

ans. The combinational circuit which performs the addition of two bits is called half adder. It has two binary inputs and two binary outputs i.e., Sum (S) and Carry (C).

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ans. The combinational circuit that performs the addition of three bits and gives the outputs as Sum and Carry is called Full adder.

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3. What is Half Subtractor?

ans. The combinational circuits that perform subtraction of two binary bits and gives the result as Difference and Borrow are called Half Subtractor.

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4. What is Full Subtractor?

ans. The combinational circuit that performs the subtraction of three binary bits is called Full Subtractor. The disadvantage of a half subtractor is overcome in full subtractor.

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5. What is Multiplexer?

ans. A Multiplexer which is also called MUX or Data Selector is a logic circuit that has many data inputs and allows only one of the input at a time to get through the output.

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6. What is De-Multiplexer?

ans. A De-Multiplexer which is also called DEMUX performs a reverse operation of a multiplexer i.e., it has only one input, ‘n’outputs and ‘m’select inputs. Only one output line is selected at a time by the select lines and the input is transmitted to the selected output line.

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7. What is Encoder?

ans. The Encoder is a combinational circuit that has a number of inputs out of which only one input is activated at a time and produces ‘m’output lines depending on which input is activated.

8. What is Decoder?

ans. A Decoder is a logic circuit that converts ‘n’ bit binary input code to ‘m’output lines in a way that only one output is activated for each one of the possible combinations of inputs.

9. What is Flip-Flop?

ans. Flip Flop is a sequential circuit which is a binary storage device. It can store either 0 or 1. It has two stable states i.e., HIGH and LOW or 1 and 0. It remains in one state until it is directed by an input signal to switch over to the other state. It is also called as bi-stable multi-vibrator.

10. What is the SR flip flop?

ans. The SR flip flop is the simplest flip flop that can be constructed using NOR gates or NAND gates.

11. What is D flip flop?

ans. The modified form of clocked SR flip flop is a D flip flop. The D flip flop has only one input in addition to the clock pulse.

12. What is T flip flop?

ans. The T in T flip-flop represents a toggling operation. The applications of T flip-flop are counters and control circuits. T flip flop is a modified form of JK flip-flop making it operate in the toggling region.

13. What is Counter?

ans. Counters are a special type of sequential circuit which is used to count the pulse or a collection of flip flops where the clock signal is applied is known as counters. Based on the clock pulse, the output of the counter contains a predefined state. The number of the pulse can be counted using the output of the counter.

So Guys! These were the basic questions you can prepare for the interviews. Hope it would be useful and Good Luck!