# EC GATE 2007 (Test 2)

Tag: ec gate 2007
Q.1
The Boolean function Y = AB + CD is to be realized using only 2 - input NAND gates. The minimum number of gates required is
A. 2
B. 3
C. 4
D. 5
Explaination / Solution:

This is SOP form and we require only 3 NAND gate

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Q.2
For the circuit shown, the counter state (Q1Q0) follows the sequence

A. 00,01,10,11,00
B. 00,01,10,00,01
C. 00,01,11,00,01
D. 00,10,11,00,10
Explaination / Solution:

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Q.3
In a transconductance amplifier, it is desirable to have
A. a large input resistance and a large output resistance
B. a large input resistance and a small output resistance
C. a small input resistance and a large output resistance
D. a small input resistance and a small output resistance
Explaination / Solution:

In the transconductance amplifier it is desirable to have large input resistance and large output resistance.

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Q.4
In the Digital-to-Analog converter circuit shown in the figure below, VR = 1V and R = 1kΩ

The voltage V  is
A. −0.781 V
B. −1.562 V
C. −3.125 V
D. −6.250 V
Explaination / Solution:
No Explaination.

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Q.5
For the BJT circuit shown, assume that the β of the transistor is very large and VBE = . V. The mode of operation of the BJT is

A. cut-off
B. saturation
C. normal active
D. reverse active
Explaination / Solution:

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Q.6
A plane wave of wavelength λ is traveling in a direction making an angle 300 with positive x − axis and 900 with positive y − axis. The  field of the plane wave can be represented as (E is constant)
A.
B.
C.
D.
Explaination / Solution:

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Q.7
In the following scheme, if the spectrum M(f) of m(t) is as shown, then the spectrum Y(f) of y(t) will be

A.
B.
C.
D.
Explaination / Solution:

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Q.8
The field in a rectangular waveguide of inner dimension a × b is given by
Where H0 is a constant, and a and b are the dimensions along the x − axis and the y − axis respectively. The mode of propagation in the waveguide is
A. TE20
B. TM11
C. TM20
D. TE10
Explaination / Solution:

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Q.9
Two 4-array signal constellations are shown. It is given that φ1 and φ2 constitute an orthonormal basis for the two constellation. Assume that the four symbols in both the constellations are equiprobable. Let N0/2 denote the power spectral density of white Gaussian noise.

The if ratio or the average energy of Constellation 1 to the average energy of Constellation 2 is
A. 4a2
B. 4
C. 2
D. 8
Explaination / Solution:

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Q.10
If the closed-loop transfer function of a control system is given as  then It is
A. an unstable system
B. an uncontrollable system
C. a minimum phase system
D. a non-minimum phase system
Explaination / Solution:

In a minimum phase system, all the poles as well as zeros are on the left half of the s −plane. In given system as there is right half zero (s = 5), the system is a non-minimum phase system.

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