In this article, we are going to learn about the Digital Electronics Interview Questions And Answers in a very detailed manner. This question we have covered is most important for interviews.

**You can also Buy the best books to learn more about the digital electronics subject. You can purchase from the below link:**

List Of Best Books For Digital Electronics For GATE, ESE PSUs

Also read

**AND Gate Truth Table – Details, Symbol & Circuit Diagram****What is VRLA Battery?****Cathode Ray Oscilloscope (CRO)****OSI Reference Model: Layers, Characteristics, Functions**

**Digital Electronics Interview Questions**

**Que.1: Given two X-OR gates, make one as a buffer and one as an inverter.**

**Answer:** If we tie one input of X-OR as 1 then it will act as an Inverter. If we tie one input of X-OR as 0 then it will act as a Buffer.

**Que.2: Tell some applications of Buffer.**

**Que.2: Tell some applications of Buffer.**

**Answer:** They are used to introduce delays in digital circuits. They are used to eliminate cross-talk due to inter-electrode capacitance due to close routing. They are used to support high fan-out.

**Que.3: Give two methods of converting a two-input NAND gate to an inverter.**

**Answer: Method 1:** Short both the inputs of the NAND gate and apply the signal then it will act as an Inverter.** Method 2:** Connect the output to one of the inputs and the other to the input signal.

**Que.4: Why are most interrupts active low?**

**Answer: **If you consider the transistor level of a module, active low means the capacitor in the output terminal gets charged or discharged based on low-to-high and high-to-low transition respectively. When it goes from high to low it depends on the pull-down resistor that pulls it down and it is relatively easy for the output capacitance to discharge rather than charge. hence people prefer using active low signals.

**Que.5: Difference between Latch and Flip-flop.**

**Answer:** The latch is a level-sensitive device whereas the flip-flop is an edge-sensitive device. flip-flops are made up of latches only.

**Que.6: What is a multiplexer?**

**Answer:** It is a combinational circuit that selects binary information from one of many input lines and directs it to a single output line.

**Que.7: What is a major advantage of R-2R ladder**** DAC**** as compared to binary-weighted DAC?**

**Answer:** The R-2R ladder uses only two values of resistors in the circuits while n binary-weighted DAC various values of resistors are required which depends on the number of binary bits.

**Que.8: What is the accuracy of a**** Digital to Analog Converter****?**

**Answer:** It is the comparison between the actual output of the converter and its expected output.

**Que.9: No. of unused states in the 3-bit Jhonson’s counter is?**

**Answer:** To find out the unused states in Jhonson’s Counter we can use the formula: **2 ^{n}-2n**. So unused states in the 3-bit Jhonson’s counter = 2

^{3}-6 =2

**Que.10: What is Digital Gate?**

**Answer:** Digital gates are basically electronic components that are used for switching and manipulating binary data

**Que.11: What do you mean by the universal gate?**

**Answer:** The universal gates are those from which we can make any gate by using them. The universal gates are: NAND and NOR

**Que.12: What is a magnitude comparator?**

**Answer:** A digital comparator or magnitude comparator is a hardware electronic device that takes two numbers as input in binary form and determines whether one number s greater than, less than, or equal to the other number.

Comparators are used in the central processing units (CPU) and microcontrollers.

**Que.13: What is Flip-flop?**

**Answer:** Flip-flop is a sequential device that is used to store 1 bit.

**Que.14: How many types of flip-flops are used in digital circuits?**

**Answer:** J-K flip-flop, S-R flip-flop, D flip-flop, T flip-flop.

**Que.15: What is the disadvantage of SR flip-flop?**

**Answer:** In SR flip-flop, if both the inputs are at logic 1 then it gives invalid output.

**Que.16: What is the disadvantage of the JK flip-flop?**

**Answer:** In JK flip-flop there will be a race around the condition that occurs when both the inputs are at logic 1. To remove race-around conditions, we have to use a master-slave flip-flop or we have to use an edge-sensitive flip-flop.

**Que.17: What is the race-around condition of the JK flip-flop?**

**Answer:** For the JK flip-flop, if J=K=1, and if clk=1 for a long period of time, then output Q will toggle as long as CLK remains high which makes the output unstable or uncertain. This is called a race-around condition in the JK flip-flop.

**Que.18: What is the Shift register?**

**Answer:** The shift register is a device that is used for storing and processing the bit in serial or parallel.

**Que.19: What are the types of Shift registers?**

**Answer:** Serial In Serial Out (SISO), Serial In Parallel Out (SIPO), parallel In Serial Out (PISO), Parallel In Parallel Out (PIPO)

**Que.20: What is Setup Time?**

**Answer:** A minimum time period during which data must be stable before the clock makes a valid transition. For example: For a positive edge-triggered flip-flop having a setup time of 2 ns then input data should be stable for 2 ns before the clock make a valid transition from zero to one.

**Que.21: What is Hold Time?**

**Answer: **A minimum time period during which data must be stable after the clock has made a valid transition. For example: For an edge-triggered flip-flop, with a hold time of 1 ns, then input data should be stable for at least 1 ns after the clock has made the transition.

**Que.22 What does Boolean algebra deal with?**

**Answer:** **Boolean algebra** is the category of algebra in which the variable’s values are the truth values,** true and false,** ordinarily denoted 1 and 0 respectively. It is used to analyze and simplify digital circuits or digital gates. It is also called **Binary Algebra** or **logical algebra.**

**Boolean Algebra Operations:**

- The basic operations of Boolean algebra are as follows:

- Conjunction or AND operation
- Disjunction or OR operation
- Negation or Not operation

**Que.23 What are the different ways of minimizing logical expressions in a digital system?**

**Answer:** To minimize a logical expression 3 different methods are used:

**Boolean algebra:**when a number of variables are less and the output is 0 or 1.**The k-map technique:**can be used for up to 5 variables.**Tabulation method:**this method can be used for any number of variables.

**Que.24 What are the different Boolean theorems? What is the advantage of using Boolean theorems?**

**Answer:**

**Different Boolean theorems used to minimize the logic expressions are:**

- Distribution theorem
- Consensus theorem
- De Morgan’s theorem
- Transposition theorem

**Advantages of using Boolean theorems:**

- The number of logic gates was reduced.
- Speed of operation improves.
- Power dissipation decreases.
- Complexity reduces.

**Que.25 What is Dual Expression in a digital system? What is a self-dual expression?**

**Answer:**

- Dual expression is used to convert positive logic into negative logic or vice-versa.

**Self-dual expression:**when a variable dual is equal to the variable itself, it is called self-dual.

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