# Implementing Sequential Circuits with VHDL MCQ’s

This set of VHDL Multiple Choice Questions & Answers (MCQs) focuses on “Implementing Sequential Circuits with VHDL”.

1. Which of the following sequential circuit doesn’t need a clock signal?
a) Flip flop
b) Asynchronous counter
c) Shift register
d) Latch

2. The following timing diagram shows ______ flip flop.

a) T flip-flop
b) D flip-flop
c) SR flip-flop
d) JK flip-flop

3. A sequential logic can’t be executed by concurrent statements only.
a) True
b) False

4. The process used for implementation of sequential logic in VHDL is called ______ process.
a) Sequential process
b) Combinational process
c) Clocked process
d) Unclocked process

5. A user has designed JK flip flop by using the VHDL code. The output is continuously switching between 0 and 1. This condition is known as _______
a) Switching condition
b) Master slave condition
c) Race around condition
d) Edge triggered condition

6. Why do we need to define clock signal in the sensitivity list of the process?
a) To trigger the statement as soon as there is some event on clock
b) To trigger the clock signal as soon as there is some event on input
c) To trigger the clock signal as soon as there is some event on output
d) To trigger the statement as soon as there is some event on input

7. Which of the following method is not used to remove the race around condition in a flip flop?
a) Using level triggered flip flop
b) Using master slave flip flop
c) Using edge triggered flip flop
d) All of the above are used to remove the race around

8. Which of the following line is correct for detecting positive edge of a clock?
a) IF (clk’EVENT AND clk = ‘0’)
b) IF (clk’EVENT AND clk = ‘1’)
c) IF (clk’EVENT OR clk = ‘0’)
d) IF (clk’EVENT OR clk = ‘1’)

9. Which of the following attribute is generally used in implementation of sequential circuits?
a) ‘STABLE
b) ‘LENGTH
c) ‘LAST_EVENT
d) ‘EVENT

10. A user doesn’t want to use the IF statement for detecting clock edge. It is possible to do the same by using any other keyword in VHDL.
a) True
b) False