Digital Electronics Questions and Answers for Viva

Answer-1: Digital electronics is a branch of electronics that deals with digital signals, which have discrete values representing binary digits (0s and 1s).

Answer-2: The fundamental unit of digital information is a binary digit, or bit, which can have a value of either 0 or 1.

Answer-3: A logic gate is an electronic component that performs a specific logical operation on one or more binary inputs to produce a single binary output.

Answer-4: The basic logic gates are AND, OR, NOT (inverter), NAND, NOR, XOR (exclusive OR), and XNOR (exclusive NOR).

Answer-5: The truth table for an AND gate shows that the output is high (1) only when all inputs are high; otherwise, the output is low (0).

Answer-6: The truth table for an OR gate shows that the output is high (1) when at least one input is high; otherwise, the output is low (0).

Answer-7: The truth table for a NOT gate shows that it produces the complement of the input, i.e., if the input is 0, the output is 1, and vice versa.

Answer-8: A decoder is a combinational circuit that converts a binary code into a specific set of output lines, while a demultiplexer is a digital switch that selects one of several input lines and routes it to a single output line based on control inputs.

Answer-9: A flip-flop is a sequential logic circuit that stores one bit of data. It can be in one of two stable states (0 or 1) and can change its state based on control signals.

Answer-10: The common types of flip-flops include SR (Set-Reset), D (Data or Delay), JK, and T (Toggle).

Answer-11: An SR flip-flop has two inputs, S (Set) and R (Reset). When S=1 and R=0, the flip-flop sets to 1. When S=0 and R=1, it resets to 0. When both S and R are 0, the flip-flop maintains its previous state.

Answer-12: A multiplexer is a combinational circuit that selects one of several input data lines and routes it to a single output line based on control inputs.

Answer-13: A counter is a sequential logic circuit that counts the number of clock cycles and generates output patterns based on the count.

Answer-14: Synchronous counters use a common clock signal to synchronize the state transitions of all flip-flops, while asynchronous counters have flip-flops triggered by the output of preceding flip-flops.

Answer-15: A binary adder is a digital circuit that performs addition of binary numbers. The most common type is the full adder, which adds two binary digits along with a carry input from a previous stage.

Answer-16: A shift register is a sequential logic circuit that stores and shifts data in serial or parallel form. It can shift data either left or right in response to clock pulses.

Answer-17: A JK flip-flop has three inputs: J (Set), K (Reset), and a clock input. When J=1 and K=0, the flip-flop sets to 1. When J=0 and K=1, it resets to 0. When both J and K are 1, the flip-flop toggles its state.

Answer-18: A logic family is a set of electronic logic circuits implemented using similar technology, operating principles, and voltage levels. Examples include TTL (Transistor-Transistor Logic) and CMOS (Complementary Metal-Oxide-Semiconductor).

Answer-19: A D flip-flop, also known as a data or delay flip-flop, has a single data input (D) and a clock input. The output Q follows the D input when the clock signal transitions from low to high (rising edge).

Answer-20: A comparator is a digital circuit that compares two analog voltages and produces an output based on their relative magnitudes. It typically generates a digital output indicating whether one voltage is greater than, equal to, or less than the other voltage.