Electronics and Communication Engineering - Digital Electronics

26. 

For the ring oscillator shown in the figure, the propagation delay of each inverter is 100 pico sec. What is the fundamental frequency of the oscillator output __________

A. 10 MHz
B. 100 MHz
C. 1 GHz
D. 2 GHz

Answer: Option D

Explanation:

T = 500 x 10-12 = 5 x 10-10

= .


27. 

If A is 1011, A" is

A. 1011
B. 0100
C. 1100
D. 1010

Answer: Option A

Explanation:

Taking 2's complement twice gives the original number.


28. 

Which of the following is not a characteristic of a flip flop?

A. It is a bistable device
B. It has two outputs
C. It has two outputs are complement of each other
D. It has one input terminal

Answer: Option D

Explanation:

Flip-flop has more than 1 input.


29. 

The number of flip flops needed for a Mod 7 counter are

A. 7
B. 5
C. 3
D. 1

Answer: Option C

Explanation:

23 = 8 If 3 flip-flops are used the modulus can be a maximum of 8.


30. 

For AB + A C + BC = AB + A C the dual form is

A. (A + B) (A + C)(B + C) = (A + B)(A + C)
B. (A + B ) (A + C)(B + C) = (A + B)(A + C)
C. (A + B) (A + C) (B + C) = (A + B) (A + C)
D. none of the above

Answer: Option A

Explanation:

Change OR to AND and vice versa.