Consider the partial implementations of a 3-bit modulus 8 up-coun
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Consider the partial implementations of a 3-bit modulus 8 up-counter as shown below. To complete the circuit, input X should be
A. X = Q<sub>1</sub> + Q<sub>2</sub>
B. X = Q<sub>1</sub>Q<sub>2</sub>
C. X = Q<sub>0</sub>Q<sub>1</sub>
D. <span class="math-tex">\({\rm{X}} = {\rm{}}{{\rm{Q}}_0}\;\overline {{Q_1}}\)</span>
Please scroll down to see the correct answer and solution guide.
Right Answer is: C
SOLUTION
The characteristic equation of T flip-flop is:
Qn+1 = T ⊕ Qn
The excitation table is as shown below:
|
Present states |
Next state |
Input |
||||
|
Q2 |
Q1 |
Q0 |
Q2 |
Q1 |
Q0 |
T2 |
|
0 |
0 |
0 |
0 |
0 |
1 |
0 |
|
0 |
0 |
1 |
0 |
1 |
0 |
0 |
|
0 |
1 |
0 |
0 |
1 |
1 |
0 |
|
0 |
1 |
1 |
1 |
0 |
0 |
1 |
|
1 |
0 |
0 |
1 |
0 |
1 |
0 |
|
1 |
0 |
1 |
1 |
1 |
0 |
0 |
|
1 |
1 |
0 |
1 |
1 |
1 |
0 |
|
1 |
1 |
1 |
0 |
0 |
0 |
1 |
