# Electronics and Communication Engineering - Exam Questions Papers

21.

Assertion (A): The small signal analysis of a transistor amplifier is done to obtain the current gain, voltage gain and the conversion efficiency of an amplifier.

Reason (R): The small signal analysis of a transistor amplifier uses the small signal parameters of the transistor.

 A. Both A and R are individually true and R is the correct explanation of A B. Both A and R are individually true but R is not the correct explanation of A C. A is true but R is false D. A is false but R is true

Answer: Option D

Explanation:

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22.

Following information is given:

1. x(z) has two poles at z = and z = - 1
2. x(1) = 1, x(- 1) = 1
3. ROC includes
Then x(n) is:

 A. u(n) + (-1)n u(- n - 1) B. 2 u(n) + (-1)n u(- n - 1) C. 2 u(n - 1) + (-1)n - 1 u(- n) D. None

Answer: Option B

Explanation:

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23.

Average power for δ(t)dt signal is __________ .

 A. B. 1 C. 0 D. ∞

Answer: Option A

Explanation:

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24.

The feedback configuration and the pole-zero locations of G(s) are shown below. The root locus for negative values k, i.e., for -∞ < k < 0, has breakaway/break in points and angle of departure at pole P (with respect to the positive real axis) equal to

 A. ± 2 and 0° B. ± 2 and 45° C. ± 3 and 0° D. ± 3 and 45°

Answer: Option B

Explanation:

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25.

Consider the following, logic diagram :

The count sequence of the above logic diagram is :

 A. 0000 to 1111 B. 0000 to 1001 C. 0000 to 1010 D. 1001 to 0000

Answer: Option B

Explanation:

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