Getting into the I.I.T.s is your aim, taking you there is ours.

Sample Test Paper EC: Electronics and Communication

Duration : 20 Min. Maximum Marks :16

2805/GATE/EC/SampleTest_EC/Pg.1

Vidyalankar

1. The Boolean Expression : B E is a simplified version of expression : ABE BCDE BCDE ABDE BCDE ABDE+ + + + + then which of the following choice is correct :

(i) dont care conditions dont exist

(ii) dont care conditions exist

(iii) d (16, 18, 20, 23, 27, 29) is the set of dont care conditions

(iv) d (16, 20, 22, 27, 29) is the set of dont care conditions

Choices :

(A) i only (B) ii and iii only

(C) ii and iv only (D) Data insufficient.

2. The matrix eAt is given as

2t

2t 4t 4t

e 0

1 1e e e

2 2

+

the value of state matrix A is given

by __

(A) 2 1

0 4

(B) 2 1

0 4

(C) 2 0

1 4

(D) 2 0

1 4

3. An angle modulated signal is expressed as

( ) ( )C is t A cos t= The angular velocity of phasor s(t) is

(A) ( )id

tdt (B) ( )

2

i2

dt

dt

(C) ( )i tt

(D) ( )

2

i

0

t dt

pi

Q.1 4 carry one mark each

Getting into the I.I.T.s is your aim, taking you there is ours.

2805/GATE/EC/SampleTest_EC/Pg.2

4. A system has a transfer function

2

1 2

1

s (1 sT )(1 sT )+ +

Its polar plot is

(A) (B)

(C) (D)

5. Consider the figure as shown

For the circuit shown above, the validity of constraint Y = Ya + Yb will be satisfied if and

only if

(A) V1 > V2 (B) V1 < V2

(C) V1 = V2 = 0 (D) V1 = V2 0

= =

= = 0

=

= 0 =

= 0

Na

Nb

Na

Nb

V1 V2

+

+

V +

V

+

Q.5 10 carry two marks each

Getting into the I.I.T.s is your aim, taking you there is ours.

2805/GATE/EC/SampleTest_EC/Pg.3

6. For a certain Si npn transistor operated at cutoff, the relation between CB reverse short

circuit current gain (R) to CB forward current gain (F) is 1 : 3. Then maintaining VBE constant, the relation valid for R, F is

(A) R F + = 1

(B) 4R F4.7 10 + = 1

(C) 6 R F4.27 10 + = 1

(D) 6 6R F4.27 10 4.27 10 + = 1

7. When the angular frequency in figure is varied from 0 to , the locus of the current phasor I2 is given by

(A) Figure (c) (B) Figure (b)

(C) Figure (d) (D) Figure (a)

Figure (a) Figure (b)

Figure (c) Figure (d)

Figure

Getting into the I.I.T.s is your aim, taking you there is ours.

2805/GATE/EC/SampleTest_EC/Pg.4

8. What is the correct sequence of the following steps in the fabrication of a monolithic

bipolar junction transistor.

1. Emitter Junction 2. Base diffusion

3. Buried layer formation 4. Epi layer termination

(A) 3, 4, 1, 2 (B) 4, 3, 1, 2

(C) 3, 4, 2, 1 (D) 4, 3, 2, 1

9. ( )pe

dx

ln x

is _________ for p 1

(A) convergent (B) divergent

(C) convergent as well as divergent (D) none of these

10. The PDF of a Gaussian random variable X is given by

2(x 4)

18x

1P (x) e

3 2

= pi

. The

probability of the event { X = 4} is

(A) 1

2 (B)

1

3 2pi

(C) 0 (D) 1

4