# Electronics and Communication Engineering - Exam Questions Papers

16.

A message signal x(t) is amplitude modulated with carrier c(t).
x(t) = 2 sin 600pt
c(t) = 8 cos (2p x 106 t)
such that the modulated signal is
(8 + 2 sin 600pt) [cos 2p x 106 t]
The total side band power is:

 A. 2ω B. 3ω C. 1ω D. 0.5ω

Explanation:

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17.

The cross section of a JFET is shown in the following figure. Let Va be - 2 V and let Vp be the initial pinch-off voltage. If the width W is doubled (with other geometrical parameters and doping levels remaining the same), then the ratio between the mutual transconductances of the initial and the modified JFET is

 A. 4 B. C. D.

Explanation:

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18.

Simplify : A + B + A B + (A + B)AB + C(B + AB)

 A. B + A B. C C. C D. 1

Explanation:

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19.

Which one of the following driving point functions does not represent an LC network?

 A. B. C. D.

Explanation:

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20.

A 2 μF capacitor is shunted by a 1 kΩ maintained at temperature 400 K. The rms noise voltage across the capacitor over the entire frequency band is:

 A. 6.25 x 10-8 V B. 5.25 x 10-6 V C. 6.25 x 10-6 V D. 5.25 x 10-8 V