10+ RTL Design Engineer Interview Questions and Answers

The setup time and hold time in a flipflop are typically set by the designer during the design phase.

• Setup time and hold time are parameters specified by the designer in the flipflop's datasheet.

• The designer ensures that the setup time and hold time requirements are met to prevent timing violations.

• Setup time is the minimum time before the clock edge that the data input must be stable.

• Hold time is the minimum time after the clock edge that the data input must be stable.

Mux and De-Mux can be used to implement logic gates.

• Mux can be used to implement OR gate by selecting one of the inputs.

• De-Mux can be used to implement AND gate by selecting one of the outputs.

• Mux and De-Mux can be used together to implement any logic gate.

• Mux and De-Mux can also be used to implement arithmetic circuits like adders and multipliers.

To calculate 64*x where x is 32 bit without using operator in Verilog code.

• Use shift left operation to multiply x by 64 (2^6).

• Shift x left by 6 bits to achieve the result.

• Ensure proper handling of overflow or truncation if necessary.

A 4 to 1 multiplexer can be implemented using two 2 to 1 multiplexers.

• Connect the select inputs of the two 2 to 1 multiplexers to the two most significant bits of the 4 to 1 multiplexer.

• Connect the data inputs of the two 2 to 1 multiplexers to the corresponding data inputs of the 4 to 1 multiplexer.

• Connect the outputs of the two 2 to 1 multiplexers to the two inputs of a third 2 to 1 multiplexer.

• Connect the output of the third 2 to 1 multiplexer to the output of the 4 to 1 mu...read more

A latch is level sensitive and a flip-flop is edge sensitive. Latch changes output as soon as input changes, while flip-flop changes output only on clock edge.

• Latch is level triggered, while flip-flop is edge triggered

• Latch changes output as soon as input changes, while flip-flop changes output only on clock edge

• Latch is asynchronous, while flip-flop is synchronous

• Examples: SR latch, D latch for latch; D flip-flop, JK flip-flop for flip-flop

A full adder is a digital circuit that performs addition of three binary numbers.

• Create three input bits A, B, and Cin

• Calculate the sum bit (S) and the carry out bit (Cout)

• Use XOR gates for sum and AND gates for carry out

• Example: A = 1, B = 1, Cin = 0, S = 0, Cout = 1

FIFO design in Verilog involves creating a First-In-First-Out buffer for storing and retrieving data.

• Use Verilog code to define a FIFO module with input and output ports.

• Implement logic for writing data into the FIFO and reading data out in sequential order.

• Ensure proper synchronization and handling of full and empty conditions.

• Test the FIFO design using simulation tools like ModelSim.

• Consider parameters like depth, width, and clock frequency for optimal performance.

A mod counter is a counter that counts from 0 to a specified modulus value before resetting to 0.

• Design a counter with a specified number of bits to represent the count value

• Implement logic to increment the count value by 1

• Add logic to reset the count value to 0 when it reaches the modulus value