EC Mock Test-3

8/13/2019 EC Mock Test-3

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Model Test Paper - IIIGATEElectronics & Communication

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Practice Paper-III EC

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Q. 1 - Q. 25 carry one mark each.

Q.1 Match list - I (State of operation of an N-MOSFET) with List - I I (Required condi-tion) and choose the correct option.

List - I List - II

P. OFF 1. V V>gs thandV V Vgs thandV V V>ds gs th-^ hR. Non - linear 3. V V>gs th

S. Saturation region 4. V V


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Q.5 Consider the pole-zero configurations shown in figure below.

Which of the following networks correspond to above shown pole zero configuration ?

(A) Phase lead network (B) Phase lag network

(C) Phase lead-lag network (D) Non minimum phase network

Q.6 Consider the architecture of a two stage op-amp shown below.

The stage marked X is

(A) Direct coupled amplifier (B) Buffer amplifier

(C) Level shifter (D) Blocking oscillator

Q.7 The probability of picking 3 symbols are respectively P0, P1and P2respectively. Toachieve the maximum entropy the probabilities P0, P1, and P2will be respectively

(A) , ,31

21

31 (B) , ,

41

41

21

(C) , ,31

31

31 (D) , ,0 1 0

Q.8 Consider a circuit shown in the figure below. The voltage across 5Wresistor is mea-

sured to beVo. I f a finite resistance is connected in series with 5Asource, then value ofVo.


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(A) decreases

(B) increases

(C) remains unchanged

(D) none of these

Q.9 Which of the following has driving point impedance equal to ( ) / 2 0.25Z s s1= +^ h

Q.10 Which of the following signal is not periodic?

(A) (10 )sin t (B) 2 (5 )cos tp

(C) (10 ) ( )sin t u tp (D) none of these

Q.11 The time convolution of two functions ( )f t1 and ( )f t2 in frequency domain is equiva-lent to

(A) ( ) ( )f t f t 1 2* (B) ( ) ( )f t f t 21

1 2p *6 @

(C) ( ) ( )F j F j 1 2w w (D) ( ) ( )F F21 1 2p

w w*6 @

Q.12 Let [ ] ( ) 5 3 7x n X e e e D T F T j j j2= + +W W W- - , then sequence [ ]x n is

(A) { ,7,3}5-

(B) {5, ,7}3-

(C) {7, ,5}3-

(D) { ,3,7}5-


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Q.13 The tips of three vectorsA , B andC drawn from a point define a plane. A B C: #^ hequals to

(A) +1

(B) 1-

(C) zero

(D) cant be determined as A , B and C are not given

Q.14 Path of a charged particle A that enters in a uniform magnetic field B (pointing intothe page) is shown in the figure.

The deflection in the path of the particle shows that the particle is

(A) positive charged (B) negatively charged

(C) uncharged (D) cant be determined

Q.15 The Simplified form of the expression ...a ab abc abcd + + + +- -- ---

is

(A) b- (B) 1

(C) 0 (D) a

Q.16 A J -K Flip-flop can be made from an S-R Flip-flop by using two additional

(A) NAND gates

(B) OR gates

(C) AND gates

(D) NOR gates


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Q.17 If2

3

6

9A == Gand

y

x3

2B == G, then in order that AB 0= , the values of xand ywill

be respectively

(A) 6- and 1- (B) 6 and 1

(C) 6 and 3- (D) 5 and 14

Q.18 Let P and Q be square matrices such that PQ = I, then zero is an eigenvalue of

(A) P but not of Q (B) Q but not of P

(C) Both P and Q (D) neither P nor Q

Q.19 limx

e e 2x

x x

0 2+ -

"

- is equal to

(A) 1 (B) 1-

(C) 1/2 (D) /1 2-

Q.20 The value of integral cos xdx/

2

0

2p

# is(A) p (B) 2p

(C) 4p (D) / 4p

Q.21 The residue of coszz1at z 0= is

(A) /1 3- (B) /1 2-

(C) /1 3 (D) /1 2

Q.22 In the circuit shown below average power absorbed by resistor is

(A) 16W (B) 6.4W

(C) 8W (D) 10W


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Q.23 Consider the BJ T circuit shown below. The type of feedback present in circuit is

(A) Voltage series (B) Voltage shunt

(C) Current series (D) Current shunt

Q.24 The DTFS coefficients of a signal [ ]x n are shown in figure below.

The value of [ ]x 0is

(A) 5 (B) 2

(C) 1 (D) 3

Q.25 In Boolean algebra, the value of 1 1+ is

(A) 10 (B) 0

(C) 1 (D) 11


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Q. 26 - Q. 55 carry two marks each.

Q.26 Consider the logic circuit with input xand ' '1shown below. I f the number of XOR gates connected in the circuit is 21, then output ywill be

(A) X (B) X

(C) 1 (D) 0

Q.27 Asynchronous counter shown in figure below is

(A) Mod-21 counter (B) Mod-22 counter

(C) Mod-20 counter (D) Mod-19 counter

Q.28 Consider a stationary stochastic signal sequence x n^ h" ,with zero mean and autocorrelation sequence

otherwise

n

n

n

1

21

0

01!f =

=

=^ ^^^

h hhh

Z

[

\

]]

]]

What will be the prediction coefficient a1^ hof the 1storder minimum mean square errorpredictor for x n a x n 11= -t ^h h(A) .025 (B) .05

(C) .075 (D) .085


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Q.29 Consider the MOSFET circuit shown below. The transconductance of M1and M2are respectively gm1and gm2. I f the channel length modulation and body effect for the giventopology is neglected, then the voltage gain A V will be

(A)g R

g R

1 m Pm D

2

1

+ (B)

g R

g R

1 m Dm P

2

1

+

(C)g R

g R

1 m Dm P

1

2

+ (D)

g R

g g R R

1 m Pm m P D

2

1 2

+

Q.30 Consider a black and white television picture consisting of approximately 3 105# el-ements, each of which may occur one of 10distinct brightness levels with equal probability.

If the transmission rate is 30picture frames/second and SNR is 30dB, then the minimumbandwidth required to support the transmission of the resulting video signal will be

(A) 3MHz (B) 5MHz

(C) 7MHz (D) 9MHz

Q.31 A magnetic core of uniform cross section having two coils (Primary and secondary)wound on it as shown in figure. The no. of turns of primary coil is 5000 and no. of turnsof secondary coil is 3000. If a voltage source of 12voltis connected across the primary coil

then what will be the voltage across the secondary coil ?


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(A) 72volt (B) 7.2volt

(C) 20volt (D) 7.2volt-

Q.32 A uniform plane wave in region 1 is normally incident on the planner boundary sepa-rating regions 1 and 2. Both region are lossless and r r1 1

3e m= , r r2 23e m= . I f the 20% of the

energy in the incident wave is reflected at the boundary, the ratio /r r2 1e e is

(A) 1.48 (B) 17.9

(C) 25.6 (D) 58.3

Q.33 An infinitely long lossy transmission line with characteristic impedance 200Z01 W= is feeded by a /2l section of 100Wlossless transmission line as shown in figure. If a volt-

age generator 4VVsg = with an internal resistance 100Zg W= is applied to the wholeconfiguration then the average power transmitted to the infinite transmission line will be

(A) 2.2mWatt (B) 22.2mWatt

(C) 17.8mWatt (D) 2.2mWatt-

MCQ 34Consider the filter and the waveform of input Vishown in figure below.

The waveform of output V0is


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(A) (B)

(C) (D)

Q.35 Consider the MOSFET configuration shown below.

Which of the following waveform shows the correct relation between input and output

voltage for body bias effect.

(A) (B)

(C) (D)

Q.36 The signal space diagram of coherent QPSK is shown below. The expression forQPSK transmitted signal will be (Assume bit duration 0.25 secm= )


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(A) . cos f t i948 2 2 14c

p p

+ -^d h n (B) . cos f t i i 948 2 2 2cp p+ -^c h m

(C) . cos f t i189 2 2 14c

p p

+ -^d h n (D) . cos f t i134 2 2 1 4cp p+ -^d h n

Q.37 If a matched filter is defined as

2 . . .s t f t f t t f t t 05 25 05d d= + - + - +*^ ^ ^ ^ ^h h h h h hwhere f t^ his shown in figure below, then what will be the impulse response of matchedfilter ;h t t2 3


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Q.39 Consider the two circuits shown below. In circuit-I , M1is biased in saturation with adrain current equal to I1and the current source 0.75IIS 1= . If the gain of circuit-II is A V, then the gain of circuit-I will be

(A) A4 V (B) A2 V

(C) A V (D) A3 V

Q.40 A random bit string of length is constructed by tossing a fair coin times and settinga bit to 0 or 1 depending on outcomes head and tail, respectively. T he probability that twosuch randomly generated strings are not identical is

(A) /1 2 (B)n

1 1-

(C) !

n

1 (D) 1

2

1n

-

Q.41 If the geometric mean of ,x 20 and 40 be 20, then the value of xis

(A) 4 (B) 10

(C) 20 (D) 40

Q.42 The DT system shown in the figure below is stable if


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(A) a 2< (B) 1a (D) a 1=

Numerical Answer Questions

Q.43 The signal [ ] ( . ) [ ]x n u n 05 n= is when applied to a digital filter, it yields the followingoutput [ ]y n [ ] [ ]n n2 1d d= - - . I f impulse response of the filter is [ ]h n , then what will bethe value of sample [ ]h 1?

Q.44 Let ( , )u x t be the bounded solution of

tu xu2

2

22

22- 0= with ( , )u x

ee0 11x

x

2

2

=+-

Then what will be the value of ( , )limu t1t"3

?

Q.45 Let A be a 3 3# matrix with eigen values, , ,1 1 0- . then what will be the determi-nant of I A100+ ?

Q.46

Consider the op-amp circuit shown below. If the op-amps are ideal, then what willbe the output voltage V0(in volt) ?

Q.47 In the circuit below the switch closes at t 0= after being open for a long time. Whatwill be the value of voltage ( )v t (in volt) at t 0= +?


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Common Data Questions

Common Data for Questions 48 and 49:

A function with dont care condition is dened as , , ,f w x y z

^ h , , , , , , , ,M dc2 3 6 7 10 11 12 14 1 9P= +

^ ^h hQ.48 The minimized expression for this function without redundant term in SOP (sum ofproduct) form is

(A) wx yz xy wxz + + +- - - --

(B) wy yz xy wxz + + +- - - --

(C) xy wy wxz + +-- - - -

(D) wy xy wxz + +- - --

Q.49

The number of implicants I^ h, prime implicants PI^ h, and essential prime implicantsEPI^ hare respectively(A) I 8= , PI 4= & EPI 4= (B) I 8= , PI 4= and EPI 3=

(C) I 6= , PI 4= & EPI 5= (D) I 8= , PI 5= and EPI 3=

Common Data for Questions 50 and 51:

Consider the signal flow graph of a system shown below.


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Q.50 The number of feedback loops in the SFG is

(A) 1 (B) 2

(C) 3 (D) 4

Q.51 The number of forward paths in the SFG is

(A) 1 (B) 2

(C) 3 (D) 4

Linked Answer Questions

Statement For Linked Answer Questions 52 and 53:

In the circuit below, two series connected capacitors of 3 Fm and 6 Fm having initial voltage of4V and 6V are connected across a black box at t 0= .

For t 0$ , it is given that ( ) 20 Ai t e t m= - .

Q.52 The total energy delivered to the black box will be

(A) 300 Jm (B) 100 Jm

(C) 400 Jm (D) 200 Jm

Q.53 The energy trapped in the ideal capacitors will be equal to

(A) 32 Jm (B) 268 Jm

(C) 68 Jm (D) 132 Jm


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Statement For Linked Answer Questions 54 and 55:

Consider a semiconductor having following parametersElectron mobility, nm 7500 /cm V s

2-=

Hole mobility, pm 300 /cm v s2

-=

Intrinsic concentration ni 13.6 10 / cm11 3#=

Q.54 The conductivity of the semiconductor will be minimum if hole concentration is

(A) 68 10 / cm11 3# (B) 6.8 10 / cm15 3

#

(C) 9.8 10 / cm19 3# (D) None of these

Q.55 What will be the maximum value of resistivity ?

(A) 25 cmW- (B) 1.531 cmW-

(C) 15.31 cmW- (D) 1531.8 cmW-


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General Aptitude (GA) Questions

Q. 56 - Q. 60 carry one mark each.

Q.56 The HCF and the LCM of two numbers are 35and 272respectively. I f one of thenumbers is divided by 6, then the quotient is 11and the remainder is 4. What is the othernumber ?

(A) 90 (B) 102

(C) 124 (D) 136

Q.57 Find the sentence that has a mistake in grammar or usage. If you find no mistakes,mark choice d.

(A) The dogs barking woke us.

(B) Ursula has broke one of your plates.

(C) The sun rose from behind the mountain.

(D) No mistakes.

Q.58 Throughout the trial, the _ _ _ _ _ _ _ _ was placed on scientific evidence.

(A) enphasis (B) emphisis

(C) emphasis (D) emfasis

Q.59 son : nuclear :: _ _ _ _ _ _ : extended

(A) father (B) mother

(C) cousin (D) daughters

Q.60 general

(A) specific (B) total

(C) insignificant (D) substantial


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Q. 61 - Q. 65 carry two marks each.

Q.61 Choose the sentence that best combines the given sentences.

The federal government has diversity of jobs and geographic locations. The federalgovernment offers flexibility in job opportunities that is unmatched in the private sector.

(A) In spite of its diversity of jobs and geographic locations, the federal government of-fers flexibility in job opportunities that is unmatched in the private sector.

(B) No matter its diversity of jobs and geographic locations, the federal government of-fers flexibility in job opportunities that is unmatched in the private sector.

(C) Because of its diversity of jobs and geographic locations, the federal government of-fers flexibility in job opportunities that is unmatched in the private sector.

(D) The federal government has diversity of jobs and geographic locations, so it offersflexibility in job opportunities that is unmatched in the private sector.

Q.62 The value of ............ 67 7 7 74444

times is equal to ?

(A) 72025112

(B) 740961365

(C) 740962025

(D) 740962729

Q.63 The first term of an A Pis equal to the sum of common ratio of a GPand the firstterm of the GPis equal to the common difference of the A P. I f the sum of the first twoterms of the GPis equal to the sum of the first 2terms of the A P, then the ratio of thefirst term of the GPto the first term of an A Pis ?

(A) 1>

(B) Independent of first term of GP

(C) 1<

(D)Independent of first term of A P

Q.64 For any two numbers , ; :m n m n m n + -^ ^h h: : :mn 7 1 60= . F ind the value of : ?m n1 1

(A) :3 4 (B) :5 7

(C) :7 10 (D) :10 13


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Q.65 Ramu is planning to get wireless Internet service at his house. Two service providers,A and B, offer different rates as shown in the table below. If Ramu plans on using 25 hoursof Internet service per month, which of the following statements is true?

Internet Service RatesProvider Free Hours Base Charge Hourly Charge

A 17.5 $20.00 $1.00

B 20 $20.00 $1.50

(A) Provider A will be cheaper.

(B) Provider B will be cheaper.

(C) The providers will cost the same per month.

(D) The answer cannot be determined from the information given.

END OF THE QUESTION PAPER

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EC Mock Test-3