# Sequential Circuit

 Question 1
Consider a sequential digital circuit consisting of T flip-flops and D flip-flops as shown in the figure. CLKIN is the clock input to the circuit. At the beginning, Q1, Q2 and Q3 have values 0, 1 and 1, respectively.

Which one of the given values of (Q1, Q2, Q3) can NEVER be obtained with this digital circuit?
 A (0, 0, 1) B (1, 0, 0) C (1, 0, 1) D (1, 1, 1)
GATE CSE 2023   Digital Logic
Question 1 Explanation:
 Question 2
Consider a 3-bit counter, designed using T flip-flops, as shown below:

Assuming the initial state of the counter given by PQR as 000, what are the next three states?
 A 011,101,000 B 001,010,111 C 011,101,111 D 001,010,000
GATE CSE 2021 SET-1   Digital Logic
Question 2 Explanation:

 Question 3
A new flipflop with inputs X and Y, has the following property
$\begin{array}{|c|c|c|c|} \hline \mathbf{X} & \mathbf{Y} & \text { Current state } & \text { Next state } \\ \hline 0 & 0 & Q & 1 \\ 0 & 1 & Q & \bar{Q} \\ 1 & 1 & Q & 0 \\ 1 & 0 & Q & Q \\ \hline \end{array}$
Which of the following expresses the next state in terms of X,Y, current state?
 A $(\bar{X} \wedge \bar{Q}) \vee(\bar{Y} \wedge Q)$ B $(\bar{X} \wedge {Q}) \vee(\bar{Y} \wedge \bar{Q})$ C $({X} \wedge \bar{Q}) \vee({Y} \wedge {Q})$ D $({X} \wedge \bar{Q}) \vee(\bar{Y} \wedge {Q})$
ISRO CSE 2020   Digital Logic
Question 3 Explanation:
 Question 4
Consider the sequential circuit shown in the figure, where both flip-flops used are positive edge-triggered D flip-flops.

The number of states in the state transition diagram of this circuit that have a transition back to the same state on some value of "in" is _____.
 A 1 B 2 C 3 D 4
GATE CSE 2018   Digital Logic
Question 4 Explanation:
 Question 5
Advantage of synchronous sequential circuits over asynchronous one is :
 A Lower hardware requirement B Better noise immunity C Faster operation D All of the above
ISRO CSE 2017   Digital Logic
Question 5 Explanation:

There are 5 questions to complete.

### 5 thoughts on “Sequential Circuit”

1. please correct Qestion number 8

• Thank You PRAFUL devendra,