Electronics and Communication Engineering - Exam Questions Papers

Exercise :: Exam Questions Papers - Exam Paper 5

46.

The polar plot for positive frequencies is shown below. The gain margin is

A.	- 8.02 dB
B.	6.02 dB
C.	5 dB
D.	none of these

Answer: Option D

Explanation:

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47.

Input and output impedance with feedback for voltage series feedback having A = -200, R₁ = 10 kΩ, R₀ = 50 kΩ and feedback factor β = -0.2 will be

A.	410 kΩ, 2050 kΩ
B.	410 kΩ, 1.219 kΩ
C.	≈ 0.243 kΩ, 2050 kΩ
D.	≈ 0.24 kΩ, 1.219 kΩ

Answer: Option B

Explanation:

In voltage series feedback output impedance decreases, input impedance increases,

, R_if = R_i(1 + Aβ).

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48.

Z = __________

A.	C[A(B + C) + D]
B.	(AB + AC + D)
C.	(CA + AC + D)
D.	none of these

Answer: Option D

Explanation:

Output of first MUX = A(B + C)

Output of second MUX = C D + A B).

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49.

An FM transmitter delivers 80W to a load of 30 W when no modulation is present. The carrier is now frequency modulated by a single sinusoidal signal and the peak frequency deviation is so adjusted to make the amplitude of the second sideband is zero in the given output.
J₀(0, 0) = 1,
J₀(2, 4) = 0,
J₀(3.8) = - 0.4,
J₀(5.1)= - 0.1
J₁(2, 4) = 0.52,
J₁((3.8) = 0,
J₁(5.1) = - 0.33,
J₂(2.4) = 0.1
J₂(3.8)= 0.41,
J₂(5.1) = 0
The power in all the remaining sidebands is :