Electronics and Communication Engineering - Digital Electronics

11. 

For the gate in the given figure the output will be

A.
B. 1
C. A
D. A

Answer: Option D

Explanation:

If A = 0, Y = 1 and A = 1, Y = 0 Therefore Y = A.


12. 

In the expression A + BC, the total number of minterms will be

A. 2
B. 3
C. 4
D. 5

Answer: Option D

Explanation:

The min terms are ABC + ABC + AB C + ABC + ABC.


13. 

The circuit in the given figure is

A. positive logic XOR gate
B. negative logic OR gate
C. negative logic AND gate
D. positive logic AND gate

Answer: Option C

Explanation:

Since V(I) is lower state than V(0) it is a negative logic circuit. Since diodes are in reversed parallel, it is an AND gate.

Note: In Boolean algebra it is recognized that a positive logic OR is a negative logic AND. Similarly a positive logic AND is a negative logic OR.


14. 

Which of the following is non-saturating?

A. TTL
B. CMOS
C. ECL
D. Both (a) and (b)

Answer: Option C

Explanation:

Since it is non-saturating, ECL has low propagation delay.


15. 

The number of digits in octal system is

A. 8
B. 7
C. 9
D. 10

Answer: Option A

Explanation:

The octal system has 8 digits 0 to 7.